INTERNATIONAL

SOCIETY OF ALLIEDWEIGHT ENGINEERS, INC.

R E C O M M E N D E D P R A C T I C E N U M B E R 14

Serving the Aerospace – Shipbuilding,Land Vehicle and Allied Industries

SAWE Corporate AddressP.O. Box 60024, Terminal Annex

Los Angeles, CA 90060

Issued May 22, 2001

Revised

Weight Estimating and Margin Manual

For Marine Vehicles

Issue No. - .

Prepared byMarine Systems Government - Industry Workshop

Society of Allied Weight Engineers

in cooperation with theSociety of Naval Architect and Marine Engineers (SNAME), Ship Design – 1 Panel

All SAWE technical reports, including standards applied and practices recommended, are advisory only. Their use byanyone engaged in industry or trade is entirely voluntary. There is no agreement to adhere to any SAWE standard orrecommended practice, and no commitment to conform to or be guided by any technical report. In formulating andapproving technical reports, the SAWE will not investigate or consider patents which may apply to the subject matter.Prospective users of the report are responsible for protecting themselves against liability for infringement of patents.

Notwithstanding the above, if this recommended practice is incorporated into a contract, it shall be binding to the extentspecified in the contract.

Change Record

Issue No. Date Title/Brief Description Entered By

Forward

This Recommended Practice was developed under a joint partnership agreement with theSociety of Naval Architects and Marine Engineers (SNAME), Ship Design-1 Panel and SAWE,Marine Systems, Government – Industry Workshop, and is a product of a cooperative effort byboth professional societies. SNAME will issue this document as a SNAME Technical& Research Bulletin (T & R Bulletin # XX).

The SAWE Government – Industry Marine Systems Workshop gratefully acknowledgesthe efforts of the following section authors:

Section 3.1 Standard Coordinate System Dan Dolan

Section 3.2 Weight Classification Systems Burt Walker

Section 4.0 Weight and CG Estimating Andy Schuster Methods and Procedures

Section 5.0 Weight and CG Margins Dominick Cimino andChris Filiopoulos

Section 6.0 Weight Reporting Requirements Sebastian Phillips

Section 7.0 Weight Measurement Ray Holland

Section 8.1 Weight Moment of Inertia/ Dominick Cimino Gyradius

Section 8.2 Longitudinal Weight Distribution Burt Walker andDominick Cimino

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Table of ContentsPage

1.0 Introduction..........................................................................................................................1-1 1.1 Weight Control Program...........................................................................................1-1

2.0 Definition of Terms..............................................................................................................2-1

3.0 Standard Reference Systems ...............................................................................................3-13.1 U.S. Customary Station 0 at FP ..............................................................................3-13.2 European Customary Station 0 at A........................................................................3-33.3 Weight Classification Systems.................................................................................3-3

3.3.1 ESWBS (U. S. Navy) ..................................................................................3-43.3.2 MarAd (U. S. Commercial) .........................................................................3-43.3.3 Other Systems ..............................................................................................3-5

4.0 Weight and CG Estimating Methods and Procedures..........................................................4-14.0.1 The Process ..................................................................................................4-14.0.2 Elements of a Weight Estimate ....................................................................4-1

4.1 Basic Weight Estimating..........................................................................................4-14.1.1 Weight Control Plan.....................................................................................4-14.1.2 Calibrated Methods......................................................................................4-24.1.3 Database .......................................................................................................4-24.1.4 System Knowledge.......................................................................................4-34.1.5 Design History..............................................................................................4-3

4.2 Factoring Methods....................................................................................................4-34.2.1 Basic Weight Estimating Equation..............................................................4-34.2.2 Unit Weights ................................................................................................4-34.2.3 Fractions.......................................................................................................4-34.2.4 Algorithm.....................................................................................................4-44.2.5 Baseline ........................................................................................................4-44.2.6 Ratiocination................................................................................................4-44.2.7 Statistical......................................................................................................4-54.2.8 Volumetric Density......................................................................................4-54.2.9 Deck Area Function.....................................................................................4-54.2.10 Regulatory Bodies Rules and Industry Design Standards............................4-54.2.11 Top Down.....................................................................................................4-64.2.12 Bottom Up....................................................................................................4-74.2.13 Midship Extrapolation Method ....................................................................4-74.2.14 Percent Complete .........................................................................................4-74.2.15 Synthesis Programs………………………………………………………..4-7

5.0 Weight and Center of Gravity Margins ...............................................................................5-15.1 General ....................................................................................................................5-15.2 Commercial..............................................................................................................5-15.3 Military.....................................................................................................................5-1

5.3.1 Acquisition Margins........................................................................................5-25.3.2 Service Life Allowances .................................................................................5-2

5.4 Policy........................................................................................................................5-2

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5.4.1 Acquisition Margins.....................................................................................5-2

6.0 Reporting Requirements.......................................................................................................6-16.1 Detail Corresponding to Level of Design.................................................................6-16.2 Margins, Loading Conditions...................................................................................6-2

7.0 Weight Measurement ...........................................................................................................7-17.1 Weighing of Material and Equipment ......................................................................7-17.2 Deadweight Survey/Determination..........................................................................7-27.3 Inclining Experiment ................................................................................................7-2

8.0 Other .................................................................................................................................8-18.1 Weight Moment of Inertia /Gyradius .......................................................................8-1

8.1.1 Weight Moment of Inertia ............................................................................8-28.1.2 Gyradius .......................................................................................................8-28.1.3 Gyradius Estimated Values ..........................................................................8-2

8.2 Longitudinal Weight Distribution .......................................................................... 8-3

9.0 References .............................................................................................................................9-1

Appendix:

A ESWBS 1-Digit and 3-Digit Listing

B MarAd Weight Classification Listing

C Inclining Experiment General Guidance

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List of Figures

Figure 1. Isometric view of surface ship with standard U.S. coordinate system............ 3-1

Figure 2. Referenced origins........................................................................................... 3-2

Figure 3. High Level Weight Engineering Process........................................................ 4-1

Figure 4. Weight and KG Risk Assessment ................................................................... 5-4

Figure 5. Three Rotational Motions of a ship ................................................................ 8-1

Figure 6. Lightship 22 Station Weight Distribution ...................................................... 8-4

Figure 7. Full Load Condition 22 Station Weight Distribution .................................... 8-5

List of Tables

Table 1. Weight Estimating Database ............................................................................ 3-2

Table 2. Acquisition Margin Value Ranges by Ship Design and Construction Phases .................................................................. 5-3

Table 3. Design Characterization Ratings..................................................................... 5-5

Table 4. Risk Consequences ......................................................................................... 5-5

Table 5 Service Life Allowance Values ...................................................................... 5-6

Table 6. Estimated Gyradius Values for Surface Ships and Submarines..................... .8-2

Table 7. Lightship and Full Load Conditions................................................................ 8-4

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1-1

1.0 INTRODUCTION

The purpose of this Bulletin is to document naval architectural practices and conventions used inthe estimation and determination of the weight, centers of gravity and weight moments of inertiafor surface ships, and to reference sources of weight estimating data for ships and theircomponents for use at various stages of design. Conventions and practices for offshore drill rigs,high speed craft and submarines are mentioned in some instances to demonstrate alternativemethodologies, but are documented only by references. Military practices and conventions aresummarized and referenced but not fully documented.

Throughout this document the term weight is used to represent all the mass properties ofa ship or object. These properties include the weight, center of gravity, weight moments andweight moment of inertia. Also, throughout this document the term weight as commonlyunderstood in the maritime industry, is synonymous with mass. With that in mind, weight inU.S. customary units are measured in pounds and long tons ( 2,240 lbs.); and in SI units (metric),weight is measured in kilograms and metric tonnes (1000 kg). Refer to ASTM F 133293,Standard Practice for Use of SI (Metric) Units in Maritime Applications [1]1 for conversionfactors to convert inch pound quantities to SI (metric) quantities for units, moment, moments totrim, and so forth.

1.1 Weight Control Program

The U. S. Navy’s weight control process was essentially formalized, as a program, in themiddle 1960’s. A SNAME paper, Weight Control of U. S. Naval Ships, presented at the AnnualMeeting, in New York City, in November 1965, documented as well as highlighted key elementsof the program. Additionally, this paper is viewed by most weight engineers as the formalintroduction of the weight control program. Also, after the test of time (over 35 years), thismanual [2] is still applicable and is particularly noteworthy when considering the manysignificant technological engineering advancements that have occurred over the last threedecades. The following points paraphrase the essence of a weight control program, as it relatesto U. S. Naval ships. It is a program that includes all actions necessary to ensure that a ship’sweight and moments are consistent with approved naval architectural requirements for strength,stability and performance. It includes estimating, reporting, weighting, calculating, analyzing,and projecting. It involves making design decisions, analyses, and judgements, andrecommending specific corrective action when necessary. It is a prime function of theadministration and management of any ship design and construction project. Timeliness isconsidered one of the primary ingredients of a successful weight control program. Weightcontrol must begin with the earliest phases/milestones of a ship design and keep pace with theship’s development through transitional design, detail design, construction, delivery and into theship’s service life. Weight reporting is a necessary part of weight control and provides the bestrepresentation of the displacement, KG, list and trim of the ship at periodic times during thevarious design and construction phases. Weight reporting, by itself, is not weight control. Too,often, the submission of weight reports (the act of weight reporting) has been mistaken forweight control. An essential component of an effective weight control program is the weightcontrol plan which is developed by the shipbuilder to control the weight during the design andconstruction phases. 1 Numbers in square brackets designate References, Section 9.0

The weight control plan is an essential part of the overall weight control program. It isusually required in the contract for the shipbuilder to develop and implement a weight control plan.It is general in nature, and outlines the type of weight control measures and procedures that areconsidered in order to meet the established weight control responsibilities. It may be structured toreflect general approaches to weight control, or outline more aggressive approaches in conjunctionwith incentives clauses. Examples of a weight control plan can found in References [3, 4, and 5].However, the specific elements of the plan are developed around the contractual requirements andthe commitment to the overall mass properties goals and objectives.

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2.0 DEFINITION OF TERMS

Accepted Weight Estimate (AWE): The AWE defines the weight and center of gravity of a shipthat was awarded under a specification type contract using the information that was available atthe time of contract award. It establishes contractual values for weight and KG and is thebaseline for detail design and construction.

Acquisition Margins: Acquisition margins are weight and KG allowances included in weightestimates to account for the inherent limits of precision and the undefined variations ofcomponent weight and center of gravity that take place during design development and theconstruction of ships.

Aft Perpendicular (AP): A vertical line intended to denote the after end of a ship’s immersedbody. The AP is often placed at the centerline of the rudder stock, the after extremity of thedesign waterline or the after extremity of the sternpost.

Agreed Weight and Center of Gravity Estimate: An estimate of light ship weight and centers ofgravity data, mutually agreed upon between the owner and the shipbuilder shortly after award ofthe shipbuilding contract, based on the ship design information (i.e., specifications, drawings,and so forth) available at the time of award.

Allocated Baseline Weight Estimate (ABWE): The ABWE is the contractor’s definition of theweight and center of gravity of a ship that was awarded under a performance type contract at thetime of hull and propulsion configuration approval. It is the baseline for detail design andconstruction.

As Built Weight and Center of Gravity Estimate: A detailed final estimate of light ship weightand centers of gravity data, adjusted for inclining experiment results, reflecting the as built shipincluding the net effect of contract modifications.

Center of Gravity (CG): The center through which all weights which make up the ship and itscontents may be assumed to act. This center as it applies to a ship has the conventional meaningused in mechanics, i.e., it is the point at which the sum of the moments of all the weights in theship with reference to any axis through this point is equal to zero. Its three coordinates (VCG,LCG and TCG) are calculated by dividing the sum of each of three moments by the sum ofweights.

Concept (Basic, Feasibility) Design: The translation of the owner’s requirements, or missionrequirements, into a broad definition of an item of hardware that can be produced and operated ina manner that will satisfy the stated mission.

Contract Design: Consist of the preparation and formalization of the drawings, specifications,and other technical data required to establish the contractual base for negotiation of aconstruction contract with a shipbuilder(s).

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Contract Modification Margin: A weight and KG allowance included in the weight estimate toaccount for increases associated with contract modifications issued during the Detail Design andBuilding [Engineering and Manufacturing Development] Phase.

Detail Design: This work is usually accomplished by the shipbuilder or his agent and primarilyinvolves the preparation of detail working drawings for ship construction, procurementspecifications for the purchase of materials and planning for the ship construction, testing andtrials.

Detail Design and Building (or Engineering and Manufacturing Development [6]) Margin: Aweight and KG allowance included in the weight estimate to account for contractor responsibledesign changes to the current weight due to ship construction drawing development, growth ofcontractor furnished material, omissions and errors in the accepted weight estimate, as well asdiffering shipbuilding practices, omissions and errors in the ship construction drawings, unknownmill tolerances, outfitting details, variations between the actual ship and its curves of form, andsimilar differences.

Forward Perpendicular (FP): A vertical line drawn through the point of intersection of thedesign waterline and the forward extremity of the ship.

Government-Furnished Material Margin: A weight and KG allowance included in the weightestimate to account for increases caused by the growth in Government furnished material duringthe Detail Design and Building [Engineering and Manufacturing Development] Phase.

Gyradius: The radius of gyration for roll, pitch, or yaw is the square root of the quotient of theship’s weight moment of inertia about the roll, pitch, and yaw axes, respectively, divided by theship’s displacement.

KG: The height of the ship’s vertical center of gravity as measured from the bottom of the keel(includes keel thickness).

Longitudinal lever (LCG): The longitudinal lever is the perpendicular distance from a transverseplane through the longitudinal reference of the ship to the center of gravity of an item or group ofitems.

MarAd: The United States Maritime Administration whose overall mission is to promote thedevelopment and maintenance of an adequate, well-balanced, United States merchant marine,sufficient to carry the Nation's domestic waterborne commerce and a substantial portion of itswaterborne foreign commerce, and capable of serving as a naval and military auxiliary in time ofwar or national emergency.

Mass properties: Mass properties are those physical characteristics which define the magnitude,location, and distribution of weight in the ship. They include weight, center of gravity location,weight moments, and moments of inertia. The term "mass" is more definitive than the somewhatambiguous term "weight"; however, historical use and common practice will lead to the retentionof the word "weight" for many years as applied to the control of mass properties aboard ships.

Mid Perpendicular (MP): The halfway reference point between the FP and the AP.

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Molded Baseline: The top surface of the keel plate at its lowest point.

Moment: The product of an item’s weight multiplied by the item’s lever arm.

NAVSEA: The Naval Sea Systems Command whose overall mission is to transform militaryrequirements into naval capabilities through research, development, engineering, design,acquisition, modernization, maintenance and logistics support of effective ships, systems andweapons which enables sailors and marines to conduct timely and sustained worldwide maritimeoperations.

Pitch inertia: The moment of inertia about the transverse axis (y) through the ship's center ofgravity.

Preliminary Design: Development of the final ship proportions, arrangements, power plant type,and structural layout that will satisfy the mission requirements. Several arrangements are oftendeveloped for comparison.

Preliminary/Contract Design (or Program Definition and Risk Reduction [6]) Margins: A weightand KG allowance included in the weight estimate to account for increases associated withdesign development during the Preliminary/Contract [Program Definition and Risk Reduction]Phase.

Referenced origin: The location of the intersection of the x, y and z axes referenced to the ship,see Figure 1.

Roll inertia : The moment of inertia about the longitudinal axis (x) through the ship’s center ofgravity.

Service Life Allowances (SLAs): Weight and KG allowances included in design to accommodatechanges due to both authorized (e.g. ship alterations), and unplanned growth (e.g. accumulation ofpaint and deck covering, personal belongings, unauthorized changes, etc.) during the ship’soperational lifetime which increase displacement and impact stability. The purpose of the SLA is toassure that the ship will not exceed its draft and stability limitations, despite growth throughout itsservice life.

Transverse lever (TCG): The transverse lever is the perpendicular distance from the verticalcenterline plane of the ship to the center of gravity of an item or group of items.

Vertical lever (VCG): The vertical lever is the perpendicular distance from a horizontal planethrough the molded baseline of the ship to the center of gravity of an item or group of items.

Weight estimate: A weight estimate is a prediction of the weight and location of the center ofgravity of the ship at the time of delivery based on the definition of the design at the time theestimate is computed.

Yaw inertia : The moment of inertia about the vertical axis (z) through the ship’s center ofgravity.

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3.0. STANDARD REFERENCE SYSTEMS

3.1 U.S. Customary – Station 0 at FP

3.1.1 Standard Axes

The U.S. standard axes for surface ships are shown in Figure 1 [7]. The roll axis forsurface ships is the x-axis. It is oriented along the centerline of the ship, running forward and aft.Longitudinal dimensions are measured along or parallel to this axis. The pitch axis is the y-axis.It runs transversely port and starboard. Besides being the axis for pitch, transverse dimensionsare measured along or parallel to this axis. The yaw axis is the z axis. It runs vertically anddimensions are measured along or parallel to this axis.

Figure 1 Isometric view of surface ship with standard U.S. coordinate system

3.1.2 Center of Gravity

The distance measured vertically along the z axis from the referenced origin to the shipcenter of gravity is referred to as the Vertical center of gravity (VCG). The distance measuredlongitudinally along the x-axis from the referenced origin to the ship center of gravity is referredto as the Longitudinal center of gravity (LCG). The distance measured transversely along the y-axis from the referenced origin to the ship center of gravity is referred to as the Transverse centerof gravity (TCG).

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3.1.3 Referenced Origin

The location of the center of gravity of a surface ship is defined relative to the three axesshown in Figures 1. Distances are measured along the three axes from a referenced origin asshown in Figure 2. The recommended referenced origin for a surface ship is the intersection ofthe ship’s forward perpendicular (FP), the ship’s centerline plane and the ship’s baseline. It isrecognized, however, that the origin can also be referenced to the ship’s mid perpendicular (MP)or the aft perpendicular (AP). The VCG should have a sign convention of positive for itemsabove the referenced origin and negative for those below. For LCG the sign convention shouldbe positive for all items aft of the referenced origin and negative for those forward. For TCG thesign convention should be positive for all items on the port side and negative for those on thestarboard side. However, these LCG and TCG sign conventions are not an adopted standard inthe marine industry at this time.

Figure 2 Referenced origins

3.1.4 Calculation

The weight estimate for a ship at any stage in the design is composed of a finite numberof items. The weight of each of these items is included in the estimate along with the location ofthe item’s center of gravity (CG). This is given as the vertical (z), longitudinal (x) and transverse(y) distance of the center of gravity from the defined referenced origin. This data is sufficient tocalculate the total weight and center of gravity of the ship by simply adding the weights andmoments of the item’s center of gravity about the referenced origin.

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3.2 European Customary – Station 0 at AP

3.2.1 Standard Axes

The standard axes for surface ships using European practice are basically the same as theU.S., except for the longitudinal reference origin and transverse sign convention.

3.2.2 Referenced Origin

The location of the center of gravity of a surface ship is defined relative to the three axesshown in Figure 2. The recommended referenced origin for a European surface ship is theintersection of the ship’s aft perpendicular (AP), the ship’s centerline plane and the ship’sbaseline. It is recognized, however, that the origin can also be referenced to the ship’s midperpendicular (MP) or the forward perpendicular (FP). Although the AP is normally used, thereferenced origin can be changed as needed depending on the design or the shipyard. The VCGshould have a sign convention of positive for items above the referenced origin and negative forthose below. For LCG the sign convention should be positive for all items forward of thereferenced origin and negative for those aft. For TCG the sign convention should be positive forall items on the starboard side and negative for those on the port side..

3.3 Weight Classification Systems

The weight classification system is a method by which all weight estimates arefunctionally organized. The weight classification system provides the naval architect or weightengineer with a format for organizing weight data that will be in a consistent format. The systemallows for the grouping of materials, equipment and components of the ship in a structured orderto facilitate weight estimating, comparison to previous designs, and to assure completeness.Additionally, the weight classification system provides guidance and definition at a system andsubsystem level and aids in the preparation of a complete and accurate estimate.

A common term used in weight engineering is “weight group.” Group is a fundamentalunit of ship classification, identified by one numeric digit or an alphabetic designator. Forweight estimates and reports, a group is the first character or digit of the multi digit system. Thesummation of weights and moments for all of the three digit elements that begin with the number1 is the total for Group 1, and similarly for the other groups.

The basic weight group definition of a ship design is represented by the ship’s structure,machinery and equipment, auxiliary systems, outfit and furnishing, mission equipment,acquisition margins and loads. The system and subsystem components of a ship design aregenerally classified in a one and three digit hierarchical numeric system. The weight estimate forthe ship design will be summarized by an estimate of lightship, margins and loads.

Weight estimates will generally be categorized by one of several type of WorkBreakdown Structures (WBS) or weight classification systems. The following classificationsystems are those most commonly used in today’s weight engineering environment for thedesign of naval and commercial ship design programs.

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3.3.1 ESWBS (U. S. Navy)

The Expanded Ship Work Breakdown Structure (ESWBS) [8] is a five digit functionalclassification system. For weight reporting purposes, only the first three digits of this systemapply. The fourth and fifth single digit classification levels are used to incorporate the functionsthat support maintenance and repair needs.

There are nine one-digit groups in the ESWBS weight classification system thatcomprises the weight estimate . They are as follows:

ESWBS Description 1 Hull Structure 2 Propulsion Plant 3 Electric Plant 4 Command and Surveillance 5 Auxiliary Systems 6 Outfit and Furnishings 7 Armament M Margins, Acquisition F Loads, Departure Full

The ESWBS groups (1-7, and M) represents the projected ship design in Condition A(Lightship w/ Margins). The ESWBS group F (loads) added to the projected lightship results inCondition D (departure full load). Other unique loading conditions may added and defined byother lettrs.

As previously mentioned, the weight classification is a hierarchical numeric system. TheESWBS 1-digit groups represent the system level and the subsystem level is defined by theESWBS 3-digit elements.

Appendix A provides a complete listing of the ESWBS 1-digit groups and 3-digitelements. 3.3.2 MarAd (U. S. Commercial)

Weight estimates and reports prepared for U.S. commercial ship designs are classified inaccordance with the MarAd weight classification system [9].

The MarAd weight classification system is comprised of the three major groupings below:

Hull Structure Weight Codes 0-0 to 9-9Outfit Weight Codes 10-0 to 19-9Machinery Weight Codes 20-0 to 29-9

Appendix B provides a complete listing of the MarAd weight classification system.

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3.3.3 Other Systems

Weight estimates and reports prepared for U.S. Navy small craft designs are classified inaccordance with the weight classification system for U.S. Navy small craft [10]. This system issimilar in content to that of the ESWBS system.

A similar classification system to the ESWBS is commonly developed for non-navalships, where mission related lightship equipment and outfit is substituted for armament in Group.

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4.0 WEIGHT AND CG ESTIMATING METHODS AND PROCEDURES

4.0.1 The Process

The weight estimate is the first step in a process to predict the final weight of the shipdesign in a weight control process. The purpose of the weight control process is to insure thatthe ship will be delivered within the naval architecture limits of the hull design. The final weightof the ship is predicted using estimating methods presented in this chapter. As the detaileddesign is developed, the final detailed weight estimate is refined to include new information.The weight is confirmed by weighing individual components, assemblies and eventually thewhole ship. The final weight of the ship is monitored through a weight control process during allthe different stages of design and construction.

Figure 3 – High Level Weight Engineering Process

Weight Estimating is usually associated with the initial prediction of the final shipweight; however it is used in all phases of the process. During detail design, the weight of painton the ship may be estimated using factors because it may not be cost effective to do surface areacalculations. Estimating methods may be used as a check of the reasonableness of detailedweight calculations. During the ship weighing or inclining experiment, a surveyor may estimatethe weight of stores in a storeroom based on the available volume and a stowage factor. All ofthese examples employ the same principals of weight estimating.

4.0.2 Elements of Weight Estimating

All weight estimating methods are done in the context of an organization and there mustbe certain elements in place to insure that the weight estimating effort will be successful.

4.1 Basic Weight Estimating

4.1.1 Weight ControlThe weight estimate must be done in the context of the ship design process as governed by asound weight control program. A weight control program describes how the weight will becontrolled to be within the naval architectural limits of the ship and the implied accuracy of

Estimate Calculate Weigh

WeightControl

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estimate at each design stage. It is very easy to either spend too much effort or too little effort inpreparing a weight estimate at any point in the ship design process. During early stage shipdesign, the design manager may be interested in a weight that is accurate within +/5 % of thefinal weight. During detail design and construction, the weight of an assembly or module mayneed to be more accurately estimated for the safety of the personnel lifting it with a crane.Conversely, methods that are appropriate for early stage design may not be appropriate for thedetail design phase.

4.1.2 Calibrated Methods

A weight estimate should not be given to an internal or external customer withoutvalidating its accuracy by some independent means. Staton [11] describes this as reasonabilitychecking and states that “Some method of checking results should be part of any analyses.”While he provides several methods to quickly check weight, center of gravity, and mass inertia,he suggests that for major proposals an alternate method should be used to estimate eachcomponent or group. This can be done by using complimentary methods such as the top downmethod and the bottom up methods described below for the same design, or by a line itemadjudication of the differences between the current ship weight estimate to a similar design.However, both methods should be calibrated against a known ship or component.

4.1.3 Database

A database of ship designs, components and materials is invaluable when creating aweight estimate. The database can be as simple as an organized set of files on various subjects,or a complete software storage, retrieval and analysis program. The information in the databasemay be used as parents for a new ship, or as similar components for a ship. The basiccharacteristics are listed below in the table below.

Table 1 – Weight Estimating DatabaseType Contents ExamplesShips Naval Architecture Characteristics

Weight ReportsSystem diagramsSpecificationsPhotographsTest Reports

Magazine articlesSister shipsPervious designs studiesTechnical papers

Component ASTM or Mil StandardsVendor CatalogsVendor DrawingsEquipment SpecificationsTest recordsRecords of weighing

MachineryOutfitting

Materials SpecificationsCatalogsTables of Unit Weights or densitiesRecords of weights

Steel platePipingInsulationPaintSAWE’s Weight EngineersHandbook [12]

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4.1.4 System Knowledge

The weight estimator should have a working knowledge of the function, and arrangementof the subject of the estimate. In many design offices weight engineers are senior personnel whohave spent time building, designing, or operating ships. The weight estimator must be familiarwith the entire design and building process, and the operations of the ship. In fact someshipyards use training programs as described by Shamburger [13] and Staton [11], to establish acommon basis of understanding of the weight engineering process. The weight estimator mustbe able to interpret specifications, drawings, and system specifications. This knowledge isinvaluable when an expert opinion is required for checking a weight estimate for reasonableness.Of course diversity in the make-up of a weight estimating group is a great benefit.

4.1.5 Design History

The weight estimate must be documented so that someone can check the estimate forreasonableness and so that it can be used as a basis of estimates for future projects. The designhistory should include the reference for the baseline, and parent information, and how the datawas manipulated into an estimate. Each design office will have its own format and method todocument the basis of the estimate, such as engineering calculation or department procedures, orvalidation test reports of estimating software.

4.2 Factoring Methods

4.2.1 Basic Weight Estimating Equation

The weight estimating equation is simply a unit weight multiplied by the number of unitsplus an uncertainty. The trick to weight estimating is determining the unit weight and thenumber of units in the final ship design before the system engineers have completed the design.There are several basic methods to define the unit weight of which three are described below.The number of units is dependent on what is used for a unit weight. The uncertainty of theweight estimate is based on the estimating method, and the accuracy of the system definition atthe time of the estimate.

4.2.2 Unit Weights

The unit weight methods use a constant weight for a single item or portion of an item.Typically one thinks of a unit weight of an outfitting item such as a chair and then just counts thenumber of chairs to determine their weight. An alternative might be to determine unit weightsfor all the furniture, joiner bulkheads, and auxiliary machinery required for each passengeronboard a passenger ship.

4.2.3 Fractions

The fraction methods use a ratio between a proposed and known system.4.2.4 Algorithm

The algorithm methods use equations based on one or more variables to describe the weight ofthe ship, system, or component.

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4.2.5 Baseline

The Baseline method is the most commonly used method for estimating the weight of anew ship design. Typically, a lead ship of a class or a sister ship built for another owner is usedas a bench mark on which changes are added. For example, the parent weight estimate may havebeen made for a sister ship which was an offshore supply vessel while the new design maybe ananchor handling supply vessel that is exactly the same except it has bigger engines and isoutfitted with anchor handling gear. This method is also known as the Plus and Minus methodas described by Hogg [14].

The weight engineer will use the latest information available for the parent ship as abaseline. Ideally, the inclining experiment or a lightship survey of the parent ship should beused. These tests are not required for many marine craft, so the original weight estimate mayneed to be used. The parent ship design history will be compared to the specifications andarrangements of the new design to determine the impact of any weight changes. The time appliedto the estimate for each change must be determined so that small changes do not use as mucheffort per pound of change as a large change or one that has a significant effect on ship stability.The new ship weight estimate is the parent ship weight plus all the changes.

4.2.6 Ratiocination (scaling)

This is the second most common method used to estimate the weight of ship. It assumesthat the same principles of distortion used to define the ship’s lines in the naval architecture usedto create the new ship from a parent ship, can be applied to weight estimating. The methodmultiplies a parent ship system weight by a scaling factor to create the current ship systemweight estimate. The scaling fraction is usually based on a parameter such as ship length, beam,engine rating, etc.

Several authors have documented various algorithms used by this method. Straubinger[15] of NAVSEA presented a detailed description of the method in a paper, which has beenrepeated in the SAWE Weight Engineers Handbook [12]. Both sources give scaling fractions forthe Ship Work Breakdown Structure commonly used on naval surface ships. This method iseasy to automate with common tools such as a spreadsheet, and it has been automated in morecomplex programs such as those described by Aasen [16], Ray [17], Redmond [18], andRobbins [19]. Foreign navies also use the method as described by Orton [20].

Although the method is a useful starting point in a ship design process, it does have itslimitations. Specifically, new technologies or special features that are not common to both theparent and current ship designs are not accurately scaled. The ratiocination-based weightestimate should be corrected for these attributes.

4.2.7 Statistical

This method develops an algorithm to describe the weight of a system or weight group based ona regression analysis of multiple parent ship design designs. The regression analysis can belinear, logarithmic, polynomial, or exponential. While spreadsheets are commonly used today tocomplete the regression analysis, graphical methods can also be used as described by Scott

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[21]and in Chapter 18 of SAWE Weight Engineers Handbook [12]. This method is verycommon and is described by Hogg [14], Johnson [22], Lamb [23], Penny [24], Watson, [25]Schneekluth [26] and others. The equations derived from this method can be used in automatedweight estimating software, such as spreadsheets.

By using several parents as a baseline, this method allows the estimator to see trends thatmay not be apparent in the ratiocination method. For example a regression equation for hullsteel weight might be developed based on the cubic number of set of parent ships. Theuncertainty of the polynomial equation to exactly predict the hull steel weight for a specific cubicnumber can be calculated as described by Staton [11] and Aasen [16]. The Root-Mean-Squaresum of these uncertainties is an estimate of the uncertainty of the entire weight estimate asdescribed by Kern [27]. In practical terms, weight groups with the highest uncertainty need acloser look.

The method is extremely labor intensive because the weight estimates of the parent shipmust all be normalized to same indexing system, and a regression equation is required for eachmass property considered.

4.2.8 Volumetric Density

This method multiplies a density fraction by the volume of a space to predict the weightof the contents. The center of gravity of the estimated weight is normally assumed to be at thevolumetric center of the space. The mass gyradius of the contents is usually estimated at 33% ofthe span of the space along each principal axis. A more common example is the prediction of theballast water capacity of a tank. Typically, the molded volume of the tank is calculated first, andthen it is multiplied by a series of density fractions to cover structural deductions and the densityof seawater. This same method can be applied to a storeroom, a berthing space, or an engineroom. The density fractions can be either derived from previous ship designs, or from a simplecalculation, or from government and industry guidelines.

4.2.9 Deck Area Fraction

This method multiplies a weight fraction by the deck area of a space to predict the weightof the contents. The vertical center of gravity is assumed to be either at the center of the spaceabove the deck, 3 feet above the molded deck height for contents that are accessed by personnelwho are standing or at the molded deck height for deck coverings. The longitudinal andtransverse centers of gravity are assumed to be located at the center of the deck area in the planform. The mass gyradius is usually 33% of the span of the space along each principal axis.Along the vertical axis the span may be either the full height of the space, 6 feet or zero feet,depending on the method used to estimate the vertical center of gravity.

4.2.10 Regulatory Bodies Rules and Industry Design Standards

This method uses the hull structure and equipment specification standards found ingovernment and industry standards to estimate the size from which a weight and center ofgravity can be developed. Classification society guidelines contain equations for determining theminimum scantling sizes for structure and components. These equations and assumptions ofstandard practices are used as a basis of parametric equations.

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For example the plate thickness is sized as a function of the hydrostatic head and theunsupported span of the plate. The global and local structural dimensions that are usuallyavailable at any stage of the design process define the hydrostatic head of a tank or shell plating.Shipyard standard practices define preferred stiffener spacing which defines the unsupportedspan of the shell plating. The minimum thickness of the shell plating can therefore bedetermined, and the weight estimated based on the surface area using the deck area fractionmethod described above.

Additionally, the classification rules and industry standards often define the minimumsize and number of components required on board. For example, the classification society rulesdefine the minimum size and length of anchor chain onboard. These values can be used toestimate the weight of these components based on standard purchasing practices at the shipyard.

Care should be taken to insure that the algorithms developed by this method areapplicable to the ship under consideration. Application of classification society standards mayprove to be erroneous. However, the classification society rules for a commercial ship may beinterchangeable, since these standards are based on similar risk and load assumptions. Johnsenpresents a fine an example of this method applied to tanker design weight estimates. Ferreirodescribes a detailed comparison of design standards on the concept design weight of estimate indetail.

4.2.11 Top Down

This method begins with the total ship weight or design displacement developed fromlines plan or from a limiting displacement study. The total weight and centers of gravity areallocated to various weight groups according to estimating fractions. The fractions aredeveloped from statistical studies of similar ships. The weight is allocated down the hierarchicaltree of the work breakdown system by starting with hull, machinery and outfitting first (as in theMARAD system [9]). Next the weight is allocated down to next tier in each weight group. Inthe case of hull structure it would be allocated down to the shell, decks, bulkheads, foundation,deck house etc. Finally, when the weight is allocated to the lowest practical the individualweights are checked by using other methods for specific components. Once the lowest level ofweights has been checked and corrected for reasonableness and insertion of specific components,the whole ship weight is added up.

The advantage of a Top Down approach is that it is system focused. Since it is based onprevious ship designs, it will capture a value for all weight groups based on past practices. Thismethod can give a very quick estimate of a whole ship, without spending time on details thatmay not be known to the responsible design engineer at this early design stage.

It is very difficult to estimate the weight of specific components specified by the ownerinto the estimate in a reliable manner. For example, to do this successfully the lowest level of apropulsion system weight estimate must be subdivided between the components specified by theowner (i.e. propulsion diesel) and the remaining system (i.e. shafting, gears, and auxiliaries).The parent weight estimates used for developing the weight fraction must all be subdivided, andredeveloped.

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4.2.12 Bottom Up

This method develops an estimate of the weight at the lowest level of work breakdownsystem. These individual values are summed up the hierarchical tree to develop the total shipweight. Different estimating methods are used for each line item at the lowest level of the workbreakdown system, based on the information available at the time. This method iscomplimentary to the top down method, in that its weakness tends to be the top down’s strengthsand vice versa. The bottom up method is a useful for checking the reasonableness of the topdown method and vice versa.

4.2.13 Midship Extrapolation Method

This is a fraction method that uses the unit weight of the midship section to estimate thesteel weight of the weight of the entire hull. An algorithm that describes the bow, midship, andstern sections of the hulls as fractions of the midship section are multiplied by the respectivelengths. The method is similar to multiplying the sectional area curve by a weight per foot overthe entire length. Hogg [14] describes this method as fundamental method to estimate hullstructural weight. The method can be applied to any structural or machinery item that has avarying by similar prismatic shape.

4.2.14 Percent Complete

This method is used to develop a launch weight estimate or an estimate of the weight tocomplete at the time of lightship survey. The weight engineer estimates the amount of thesystem or change installed on the ship at a point in time. This fraction is applied to the completesystem to develop the current weight. The method describes the fraction of the whole weightestimate that has been installed or removed.

4.2.15 Synthesis Programs

Synthesis programs are used to produce Random-Order-Magnitude, concept, andfeasibility studies for most new designs. These are very sophisticated computer programs thatintegrate all engineering disciplines to predict ship physical and performance characteristicsbased on mission requirements. Typically these are proprietary programs that rely on existingdatabanks (which include weight) for each ship type to produce the initial concept. A detaildescription of these programs is beyond the scope and intent of this document but they workbasically on the synthesis concept. The synthesis is made up of several modules that develop theinitial concept design: hull geometry, hull subdivision, hull structure, appendages, resistance,propeller, machinery, weights, area and volume, etc. Specifically, with the input of a few primarydesign requirements, and manning and payloads, a preliminary inboard profile can be createdand an initial size defined. The software gets convergence on the hull geometry via severalmethods then in proceeds to the hull subdivision module, structure and down the line with eachdesign module until convergence has been obtaining for the design. The weight moduleproduces an initial weight based on a specific weight classification along with VCG and LCGestimations.

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5.0 WEIGHT AND CENTER OF GRAVITY MARGINS

5.1 General

Weight and KG margin values are needed for all ship designs in order to ensure that theestimated displacement and KG values as originally projected during the initial conceptual phase ofthe ship design are met at delivery. Regardless of whether the ships are for commercial or militaryapplications, weight and KG margins are an important element of the displacement and KGprojections for a ship design.

5.2 Commercial

For commercial applications the margin values vary depending upon the ship, design andconstruction process. For U.S. Maritime Administration (MarAd ), a value of 3% for weight and3% for KG is usually recommended, as a Detail Design and Building Margin.

5.3 Military

For Military applications (i.e., U. S. Navy Surface Ships) the margin values vary dependingupon a variety of circumstances and are discussed below.

5.3.1 Acquisition Margins

U. S. Naval ship design practice utilizes the concept of a predicted baseline weightestimate that reflects the displacement, KG, list, and trim of the ship at delivery. To achieve this,acquisition weight and KG margins are essential elements of the design practice. Margin valuesfor the specified margin accounts should be developed using a structured and systematic methodwhich assigns design risk (based on previous design experience) to the state of the design basedon a set of standard design characterization factors. These factors are subjective and uniquewithin each organization. They should be developed after careful consideration of the weightcontrol process, building methods and practices, corporate approach to weight control, and otherconsiderations that can affect the weight control program. Cimino [28] describes a methodologyfor margin selection that utilizes a set of typical design characterization factors used to selectmargins. These factors tie in statistically with historical margin growth to produce margin valuesthat are unique to the design and typically fall within the mean and mean plus one standarddeviation range. However, margin allocations should always be developed in line with thefollowing considerations:

• Historical patterns of refinement and growth as reflected in weight estimates during theprogress of a design and during shipbuilding.

• Consideration of each ship design requires individual consideration of its uniquefeatures, unknowns, indeterminates and complexities.

• Avoiding injudicious application of margins, whether excessive or insufficient whichcan result in unrealistic projections of ship displacement and KG at delivery and caneither increase shipbuilding costs related to ship size or result in expensive correctivemeasures.

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• Acquisition strategy and policies which can deviate substantially from previouspractices and design requirements and as a result can significantly impact margins.

While feasibility studies only require a single overall margin allocation for weight and one for KG,as acquisition programs develop they require more definitive weight and KG margins allocations foreach phase of the design to account for increases associated with design development and buildingduring those phases.

5.32 Service Life Allowances

Service life Allowances are also required for weight and KG since experience has shownthat the displacement and KG of a naval ship tends to increase during commissioned service.These allowances are intended to provide for reasonable growth during the ship's service lifewithout unacceptable compromise of the principal naval architectural characteristics, notablythose characteristics relating to the specific performance of hull strength, reserve buoyancy, andstability. Performance characteristics, which must be satisfied at the end of a new ship's servicelife, will be identified by dialogue with the appropriate Sponsor. Other performancecharacteristics, normally including speed and endurance, will be satisfied at delivery and arepermitted to degrade as service life growth occurs. However, predictions for thesecharacteristics, both at delivery and at the end of the predicted service life, will be prepared andreported in the Preliminary and Contract Design (or Program Definition and Risk Reduction [6])Reports. For any deviation from these values, the concurrence for the selected values shall beobtained via the Sponsor.

5.4 Policy

Acquisition Margins and Service Life Allowances shall be selected and applied as follows:

5.4.1 Acquisition Margins

Acquisition margins shall be applied to all ship designs such as: new, modified repeats,conversions or modernizations, or on a case basis as indicated by the Navy where major impacton mass properties of the ship is indicated. These acquisition margins are provided for each shipdesign phase to account for increases associated with design development and the buildingprocess. They should be tailored to the specifics of the design and shall reflect aspects such asthe uniqueness of the design, the degree of definition of developmental systems incorporated,and the assumption of risk. The amount of margin to be provided must be determined andincluded in feasibility (or Concept Exploration [6]) studies, or the feasibility study that definesthe weight and moment impacts of conversions or modernizations. Acquisition weight and KGmargins should be selected within the ranges of Table 2 for feasibility stage design, and later, forthe individual margin accounts. However, the selection range is used as a guide in determiningthe appropriate margin selection. In special cases, rational deviations from the values shownmay be considered. For example, design studies reflecting radical hull forms, exotic hullmaterials, or major subsystems which are in the early developmental stages may require largermargin allocations. Conversely, incorporating items identical to previous designs may requiresmaller margin allocations.

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Table 2 – Acquisition Margin Value Ranges by Ship Design and Construction Phases

Percentage of Displacement of the Light Ship Condition

MeanMean +1 Standard

DeviationTotal Acquisition Margin 6.0 17.5

Specific Margin accounts:Preliminary and Contract Design 0.8 4.4Detail Design and Building 4.5 9.8Contract Modification 0.4 2.1GovernmentFurnished Material 0.2 0.7

Percentage of KG of the Light Ship Condition

MeanMean +1

Standard DeviationTotal Acquisition Margins 4.8 14.5

Specific Margin accounts:Preliminary and Contract Design 2.7 6.1Detail Design and Building 1.7 5.1Contract Modification 0.3 1.9Government Furnished Material 0.1 0.4

a. The value ranges shown for Total Acquisition Margin are not developed using thestatistical or arithmetic combination of the individual margin accounts. The total acquisitionmargin values are developed by characterizing the design and applying the individual marginaccounts as they would be applied during a design . The cumulative effects, using the mean andmean plus one standard deviation are the ranges that are shown for total acquisition margin.

b. Preliminary/Contract design margins are applied to the lightship baseline weightestimate, excluding ballast. For subsequent design phases, margin values are based on theprevious values of lightship plus the margins allocated to the previous design phase.Procurement margins (i.e. Detail Design and Building, Contract Modifications and GFM) areapplied simultaneously to the resulting Preliminary/Contract Design weight estimate.

c. Risk is defined as the probability that the margin used will exceed the margin selected. Arisk assessment method may provide a general guidance of the adequacy of already selectedmargin values. The aforementioned design characterizations are related statistically to historicalmargin growths to produce margin values that are unique to the design and consistent with pastresults. The method also provides a means of assessing the risk of variation from the selectedmargin values. Characterization of design uncertainty is never precise, and so for anycharacterization a range of margin values corresponding to the mean and the mean plus one

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standard deviation in the distribution of the statistical data, is considered to have an associatedrisk that can be mitigated with various weight control programs. This design uncertaintycorresponds approximately to a risk of at most 50% chance of the estimated value beingexceeded (i.e., margin exceeded) and a 16% chance of the estimated value being underestimated(i.e., margin not fully used). Weight and KG risk assessment curves for these values have beendeveloped based on the statistical analysis and design characterizations as mentioned above, andshown in Figure 4. The curves display the values of characterization ratings between 1 and 5 andthe associated margin risk lines at the lower bound (16% chance of the margin being exceeded) andat the higher bound (50% chance of the margin being exceeded). The margin values are expressedas a percentage of Light Ship weight and KG. Table 3 defines the values for the characterizationratings. Once the appropriate total margin values have been selected a level-of- confidence (orrisk) may be associated by using Figure 4. Table 4 relates the three general levels of risk (i.e.,low, moderate and high) to the programmatic risk mitigation necessary. The selection of marginvalues with high risk must be fully justified and appropriate risk mitigation instituted.

Figure 4 – Weight and KG Risk Assessment

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Table 3- Design Characterization Ratings

RATING DESIGN CHARACTERIZATION1 Developmental design/High level of uncertainty2 New concept design/Some significant level of uncertainty3 Similar design with major changes/Some level of uncertainty4 Similar design with minor changes/Little level of uncertainty5 Follow design with minor changes/Almost no uncertainty

Table 4 – Risk Consequences

RISKASSESSMENT RISK CONSEQUENCES

HIGHDesign might not meet safety limits (subdivision, strength, service lifeallowances), might involve redesigns and schedule impacts. Extreme weightcontrol measures will be required.

MODERATERisk can be controlled by an effective weight control program thatwould involve incentives, Not-to-Exceed values, and other riskmitigation measures.

LOW Safe design with very little uncertainty and applying standard weightcontrol and reporting procedures.

5.4.2 Service Life Allowances

SLAs shall be included in all new and modified repeat designs such that, when delivered,each U. S. Navy surface ship shall be capable of accommodating the anticipated growth ofweight and KG during its service life without compromise of the hull strength, reserve buoyancy,and stability characteristics established for the class. SLAs are allocated according to the shiptype and the values shown on Table 5.

The weight and KG values in Table 5 are based on historical growth data for the ship types noted.These are the minimum values that must be provided in new construction ships. As the values inTable 5 are based on a service life of 20 years (30 years for carriers and large deck amphibiouswarfare ships), an increased SLA may be required for ships with longer projected service lives. Theincrease in SLAs should be evaluated on a case basis until there is data to update Table 5.

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Table 5 – Service Life Allowance Values

Weight a KG b

Ship Type: (Percent (%) Meters (Feet)1. Combatants 10.0 0.30 (1.0)2. Carriers 7.5 0.76 (2.5)3. Amphibious warfare ship types

a. Large deck 7.5 0.76 (2.5)b. Other 5.0 0.30 (1.0)

4. Auxiliary ship types 5.0 0.15 (0.5)5. Special ships and craft 5.0 0.15 (0.5)

Notes: a Weight percentage based on the predicted full load departure displacement at delivery b KG values based on the predicted full load departure KG at delivery

SLAs are generally depleted during the service life of a ship. Depletion of the SLA and the status ofeach ship with respect to its naval architectural limits shall be monitored throughout the ship's activeservice. Weight and/or moment compensation requirements for any alteration which unacceptablydegrades the remaining stability or reserve buoyancy allowances shall be identified.

For ships designed to carry dry cargo (i.e., auxiliary and amphibious ships), the full loaddeparture condition will include the notional dry cargo load out. For ships designed to carryliquid cargo the cargo tanks shall be considered filled to 95% of the total net volume of each tankdesigned to carry petroleum products and 100% of the total net volume of each tank designed tocarry cargo potable water or cargo reserve feed water.

For SWATH or other unique hull form designs, the minimum SLAs for weight and KG shall alsobe based on Table 4 for the applicable ship type. In addition, an analysis shall be conducted todetermine the center of anticipated SLA growth for KG. The results of this analysis shall behighlighted to the appropriate sponsor, along with rationale for values used.

SLA requirements for major modernization’s and conversions shall be assessed on a case basis. Astudy taking into account the age of the ship, the remaining service life, the available weight andKG growth potential, etc., shall be performed to determine a specific recommendation for themodernization/conversion. These values, with supporting rationale, shall be highlighted inappropriate Sponsor presentations.

5.5 Contracting Practices

When a design agent or builder accepts a contract for the design and construction of a ship,he assumes a contractual responsibility for delivering a ship that meets the mass properties relatedperformance. For a surface ship these values are usually a combination of displacement(deadweight), center of gravity, list, trim, speed, payload, and other mission critical performanceparameters.

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5.5.1 Commercial ship acquisition practices

Commercial contracting practices are dependent on the Owner’s and the shipbuilder’scontractual agreement. However, a general outline and approach is discussed in Reference [5],Section 6.

5.5.2 Military ship acquisition practices

Military (i.e., U. S. Navy Surface Ships) contracting practices are dependent on theacquisition strategy. Four types of basic acquisition approaches are discussed below:

a. Navy controlled design. Ship acquisitions are controlled by the Navy when the Navyreleases a design data package as part of the bidding process. This package contains Not-to-Exceed(NTE) weight and KG values developed by the U. S. Navy and are included as part of the contract.In addition, liquidated damages may be included in the contract clause to establish the level ofcompensation due to the Navy should the NTE values be surpassed. The goal of this type ofprocurement is to have the bidder demonstrate that a ship can be delivered at or below the NTEvalues before award of the contract. If the above values cannot be met based on the definition of thecontract design package, the bidder than should define the actions and associated costs needed toachieve the NTE values. The mechanism that demonstrates the bidder’s ability to achieve the NTEvalues is the requirement to submit an independent weight estimate with the bid response. Theindependent weight estimate should represent the bidder’s detail design and construction methodsand practices. This weight estimate is prepared by utilizing the design data package whichrepresents the contract design, since it includes contractual along with guidance drawings, shipspecifications, and certain lists and schedules of Government Furnished Equipment, and loadingfactors. Contract drawings define the geometry, arrangement, and major structure of the design.They are engineering drawings from which ship construction drawings are developed. Guidancedrawings, while not providing weight data directly, are useful in preparing such data. Piping andwiring diagrams are such drawings. Also, additional information may be used from standarddrawings, design data sheets, technical manuals, manufacturer’s catalogs, component lists, andvendor catalogs to prepare the independent weight estimate.

The other goal of this policy is to have an Accepted Weight Estimate (AWE) soon aftercontract award. The establishment of the AWE is the contractual basis which is used to determinemargin depletion responsibility and essentially measures the contractor’s weight controlperformance; therefore it excludes any Government-initiated changes.

Below is an example of a Standard Contract Clause for Weight Control which may betailored to suit the specific acquisition strategy of the contract:

“In accordance with the procedures set forth in section xxx of the Specifications, theContractor shall enter into agreement with the Government as to the AcceptedWeight Estimate (AWE) for the ship(s) under this contract, and such an agreementshall be set forth in a Supplemental Agreement. The AWE values for full loaddisplacement and vertical center of gravity above bottom of keel (KG) are thebaseline of measuring Contractor responsibility within the meaning of this clause.The aforementioned AWE values shall be equal or less than the NTE values:

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Contractor responsible Full Load Displacement xxxxxxx long tonsContractor responsible KG xx.xx feet

In the event an agreement on the AWE cannot be reached within four months aftercontract award of this contract, the NTE values become the AWE values.

The parties also recognize and agree that it is virtually impossible and completelyimpracticable to establish actual damages which would be suffered by theGovernment for the failure of the Contractor to deliver the ship(s) within the NTEvalues. Therefore in recognition of the above, the parties hereto have specificallyagreed to and established the following schedule of liquidated damages as areasonable forecast of the potential damages which would arise in the event that theContractor responsible does not meet the full load displacement and/or KG, asdetermined above exceed the NTE values:

Weight – For each whole xx ton increment in excess of the NTE displacement setforth in paragraph (a) of this clause, the Contractor shall pay to the Governmentxxxxxxx dollars up to a maximum of xxxxxxx dollars.

KG – For each whole xx.xx foot increment in excess of the NTE vertical centervalue set forth in paragraph (a) of this clause, the Contractor shall pay to theGovernment xxxxx dollars up to a maximum of xxxxxxx dollars.”

Also, list and trim requirements are set forth in the Specifications.

In addition the Government may offer monetary incentives for measures that the Contractorhas undertaken that are considered above the performance of the contract to develop someperformance area specified by the government. In such cases a Board is established that defines theevaluation period, expected performance level, and available monetary award for that period.

b. Acquisition based on performance-type specifications

For ships acquired using performance-type specifications (e.g., speed endurance, payload,etc.) the required Service Life Allowances will also be specified. In lieu of the AWE an AllocatedBaseline Weight Estimate will be generated by the appropriate shipbuilders and will be submittedwith the hull and propulsion configurations for approval by the NAVY. The Allocated BaselineWeight Estimate must satisfactorily show that the ship as proposed will meet the specifiedperformance and be delivered within specified service life allowances. Weight estimating andcontrol requirements will be included in the procurement specification. Submittal and approvaldates for the Allocated Baseline Weight Estimate will be specified in the pertinent Contract DataRequirement List (CDRL) to coincide with the submittal of the hull and propulsion configurations.

c. DoD Regulation 5000.2 –R Procurement This is the newest procurement approachestablished under Acquisition Reform. In this approach the Government describes the system (ship)objectives and the minimum acceptable requirements (thresholds) for operational performance ofthe system. A preferred concept is selected for program initiation and moves forward through thedesign development and production process. The effect of this approach to weight control andservice life allowances is currently under evaluation.

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d. Other types of acquisitionFor those acquisitions where neither of the above pertains, i.e., where a design exists which

has been built, a shipbuilder’s weight estimate will be required at the time of contract award.Examples of this type include standard barges and certain standard commercial ships and craft.

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6.0 REPORTING REQUIREMENTS

As the design progress progresses, the weight estimates for all of the ship’s componentsmust be integrated into a weight report. The weight report is used to track the total lightshipweight and centers of the ship and aids in the design process to determine if the ships hull formand size correlates to the lightship weight. As the design spiral converges, the weight report iscontinuously updated to ensure that the final estimate is as close as possible to the actual weightand maintained within the vessel’s naval architectural limits.

In addition to the final weight report, separate weight reports can also be produced for aproposed alteration to structure or equipment. The U. S. Navy categorizes weight reports intothree categories:

a. Standard reports, which include weight and moment data for a completed ship. Thesereports may be specified by the contract and may be required to be submitted atvarious stages in the design.

b. Supplementary reports, which are weight and moment reports of governmentfurnished materials. They may also be required by the contract.

c. Special reports, which are prepared by the contractor for their own use or at the request of NAVSEA. They may be required by the contract.

These reports are described, in detail, in Reference [4].

6.1 Detail Corresponding to Level of Design

When a design commences, a method is established for weight reporting. The methodshould be able to accommodate changes in weights as well as the addition of new weights. Agood tool in the development of a weight report is a computer spreadsheet program. If thespreadsheet is properly prepared, weights can be modified, added or subtracted very easily.Structural components and distributed materials should always be calculated on a weight perstandard unit basis (e.g., lb/sq. ft, lb/lineal ft.) to allow automatic recalculation of the weight andcenter when either the size or type of member is changed. This procedure will save time as thedesign is refined and hull size and scantlings are finalized.

The level of detail in the weight report will follow the level of detail in the design. In theearly stages of design, the weight report will most likely contain weight estimates at the ESWBSone digit level. These weight values will be approximate and can be based on several sourcesincluding similar ship designs and weight per area of steel structure. At this level, the weightswill provide a ball park figure which will be used to approximate propulsion, cargo capacity,manning requirements, approximate cost, etc.

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As the design continues and more details are added, the weight report will be refined. Atthe preliminary design level, the weight report is often at the ESWBS three digit element level.At this level, the weight estimate will be used to determine the stability of the ship, the hullstresses, and to select the optimum propulsion plant.

When the design reaches the contract or detail design level there is enough information toproduce a final weight report. In this estimate, every piece of equipment and structure isaccounted for, including allowances for coatings, furniture etc. The goal for this is an estimateof the actual lightship weight of the vessel within a few percent.

6.2 Margins, Loading Conditions

The weight report is an estimate of all the weights included in the lightship weight of theship. It will contain assumptions, approximations, omissions and errors. Many weight groupssuch as piping, wiring, auxiliary machinery etc. are very difficult to estimate and it is likely thatonly approximate values will be available. It is impossible to account for every piece of materialadded to the ship or to precisely estimate the weight of all weight groups. Therefore, the weightreport should include certain margins to account for these inaccuracies and to act as safetyfactors. The proper margins to be used should be determined based on experience, evaluation ofthe accuracy of the weight estimate, and the impact the particular margin will have on the design.For example, on a particular tanker design in which stability is not an issue, the margin added toVCG would not be as critical as on a RORO ship design which barely meets the stability criteria.The RORO ship should have a larger VCG margin to ensure that the vessel will meet stabilityrequirements when completed.

The Final Weight Report must include loading conditions which are calculated tocorrespond to each condition in the Trim and Stability Manual. The loading conditions arecalculated by starting with the lightship weight estimate and adding all other deadweights presentfor the particular condition. The loading condition calculations will be used to determine thestability of the ship and the hull stresses as well as the draft and trim at each condition. Theywill also be sent to the Coast Guard and classification societies as proof that the vessel meets theapplicable stability requirements.

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7.0 WEIGHT MEASUREMENT

7.1 Weighing of Material and Equipment .

A comprehensive weight control program is made up of many facets, one of the essentialelements in the program is the actual weighing of material and equipment. The credibility andconfidence of the weight estimates and reports depend on accuracy, and actual scale weights ofequipment, material and components provide the most accurate weight data.

The amount of actual weighing on a given contract depends on the degree in whichshipbuilders implement their weight control program. Some of the major factors that influencefull implementation of weight control are: the shipbuilders' confidence in the Accepted WeightEstimate or the Allocated Baseline Weight Estimate, the available Weight and KG Design andBuild Margin, liquidated damages and/or incentives assigned to the contract, and the type ofvessel being constructed. For example, most ships constructed for the U.S. Navy require aweight control program that ensures that the ship’s weight and moments be consistent with itsnaval architectural limits for displacement, strength, stability, list, trim, and performance (such asspeed, endurance, and seakeeping) [4]. Historically, those contracts that contain Not-To-Exceedlimits for weight and KG, and impose liquidated damages and incentives for weight and KGpromote shipbuilders to initiate and maintain a strong weight control program.

The following identifies the requirement for actual weighing of material and equipment insupport of a comprehensive weight control program for all surface ships:

7.1.1. The actual weight of all components and equipment greater than 500 pounds (unlessotherwise specified), both Contractor and Government furnished, shall be determined throughaccurate scale weighing along with the estimation or calculation of centers of gravity. The actualweights for materials, components, and equipment, less than 500 pounds, shall be determined ona selective or sampling basis, as determined by the contractor, to provide unit weight data.Potential candidates for actual weight determination on a selective basis include such items asinsulation, structural plates and shapes, sheathing, piping, electrical cable and the componentsand equipment less than 500 pounds. Where factors or percentages are utilized, such as forestimating and calculating paint, mill tolerance, and welding, the contractor shall substantiatethese values by supplying background information (current and historical). Historicalbackground information on paint, mill tolerance, and welding factors shall be forwarded with theBidders Independent Weight Estimate or Preliminary Allocated Baseline Weight Estimate. Thefinal values for paint, mill tolerance, and welding factors, based on current ship information, willbe forwarded with the Final Weight Report. In addition, to minimize the amount of actualweight determination at the shipbuilding site, the contractor shall require, through acquisitiondocuments, subcontractors or vendors to submit information on the current weight and center ofgravity of all major assemblies, equipment, fittings or components to be installed on the ship. Itis suggested that information be submitted by subcontractors or vendors in the followingsequence:

a. An estimate of weight and center of gravity in the proposal.

b. The calculated weight and center of gravity when the design is completed.

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c. The actual weight and calculated center of gravity when the fabrication or assembly iscompleted. [4]

7.1.2. The weighing equipment (load cells) shall be accurate to 0.25 percent of the applied loadand shall be sized at seventy-five percent of the item being weighed. The estimated center ofgravity shall be determined for all major equipment and submitted with the estimated weight.The location of the equipment center of gravity shall be defined relative to the standard three axiscoordinate system x, y, and z. The z axis is generally measured from a reference point on thebottom of the equipment and referred to as the Vertical Center of Gravity (VCG). The x-axis isgenerally measured from a reference point on the rear of the equipment and is referred to as theLongitudinal Center of Gravity (LCG). The y-axis is generally measured from a reference pointon the centerline of the equipment and is referred to as the Transverse Center of Gravity (TCG).The estimated Center of gravity shall be obtained by the summation of moments about each axisincluding a minimum of eighty percent of the weight of the subcomponents for the equipment.Equipment that is symmetrical requires no calculations for the axis of symmetry. The calculatedcenter of gravity will be based on 100 percent of components. 7.1.3. Additionally, a procedure employed by some shipbuilders in their arsenal of weightcontrol techniques is a steel plate weighing inspection process. This process actually requires thesteel maker to replace over-gauge plates at the steel mill, resulting in significant weight savings.This weight control process imposes reduced plate thickness tolerances and verifies through plateweighing and measuring that each plate is produced within a specified mill tolerance.Shipbuilders have experienced negative mill tolerance through this technique which alsoincludes a system of plate sorting that actually enhances the KG of the ship under construction.As plates are weighed, they are marked “heavy” or “light” and during actual ship constructionthe “heavy” plates are placed lower in ship construction.

7.2 Deadweight Survey/Lightship Determination.

These commonly used terms refer to determining only displacement, and the longitudinaland transverse coordinates of the center of gravity. The procedures for a deadweight survey arethe same as for an inclining experiment except that inclining weights are not used and noobservations and calculations are made for vertical locations of inventory items, KG, GM, andfree surface. NAVSEA or USCG may authorize a deadweight survey in lieu of an incliningexperiment on sister ships where a satisfactory inclining experiment has been performed andapproved for the lead ship, [29]. 7.3 Inclining Experiment .

The inclining experiment represents a key aspect of weight control and weightmeasurement. It is the means of actually weighing a vessel and measuring its center of gravity.An inclining experiment consists of moving one or more known large weights across the ship,measuring the angle of list produced, reading drafts and surveying the compartments and tanksonboard the ship. The inclining experiment is used to determine compliance with therequirements of the Weight Control Program and to provide a baseline for data concerningweight and center of gravity for use in all considerations of stability, [29]. Conducting anaccurate inclining experiment requires much coordination, cooperation and teamwork. Theinclining coordinator, usually a Naval Architect, must be attentive to the details of the

7-3

experiment. He must be willing to follow up with such things as checking that cross connectvalves are closed, venting air out of full tanks, checking for discontinuities in free surface andwaterplane characteristics, weighing and covering the inclining blocks prior to the test, ensuringthe bilge has been pumped clean and dry, verifying inclining station communications, andreviewing the curves of form, tank tables and other reference documents for consistency ofreference systems. Along with all the preplanning inclining meetings, the inclining coordinatorinvariably will be reminded that “we need to expedite this,” “let’s get this over with,” “this iscosting money and holding up ship production.” So there will be a need to overcome theresistance of people who inadvertently may compromise the accuracy of the experiment.

All ships should be inclined to a standard of accuracy that not only verifies thecontractual requirements of the Weight Control Program but is an experiment that can bevalidated, and validation normally comes in the form of another repeated experiment. Theaccuracy of an inclining experiment and the many thoughts about how to validate the experimentto compare, prove or disprove the weight estimate has been the basis for many hours ofdiscussion; it is generally accepted by most shipbuilders that the accuracy of an incliningexperiment is 0.25 feet (+/-) for KG and within 0.50(+/-) percent of displacement.

It should also be noted that the Internationa l Convention on Safety of Life at Sea requiresthat “every passenger or cargo vessel shall be inclined on completion” [3] while other vessels areto be inclined as defined and directed by the ship specification. Each regulatory agency has it’sown detailed requirements for conducting an inclining experiment. Also, ASTM F 132192,Standard Guide for Conducting a Stability Test (Lightship Survey and Inclining Experiment) toDetermine the Light Ship Displacement and Center of Gravity of a Vessel [29] describes thegeneral procedures for conducting a Stability Test.

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8.0 OTHER

8.1 Weight Moment of Inertia/Gyradius

The weight moment of inertia of a ship is calculated about the longitudinal x-axis for roll,transverse y-axis for pitch, and vertical z axis for yaw. The three rotational axes for motions areshown in Figure 5. While the inertia used in these calculations is referred to as the weightmoment of inertia (expressed in units of weight times foot squared), it is normally expressed interms of mass moment of inertia. However, since the weight estimate contains the weight of theitem rather than the mass, the use of weight moment of inertia is appropriate in lieu of massmoment of inertia. Ultimately, the value being determined in the analysis is the gyradius whichdoes not have units containing mass or weight. If the calculation is done consistently usingweight, then the proper gyradius will result. Reference [30] documents the methodology used incalculating and projecting weight moment of inertia/gyradius values. It also contains acomparative analysis of calculated weight moment of inertia values among the U. S. Naval ships,as well as the results of a sensitivity analysis on their relationship.

Figure 5: Three Rotational Motions of a Ship

8-2

The total weight moment of inertia (I) for a ship is the sum of the item weight momentsof inertia and the transference weight moments of inertia. The inertias of each item must first becalculated and then summed to give the total ship inertia. The item weight moment of inertia (Io),is calculated relative to the center of gravity of the item about its own axes, oriented in the samedirection as the ship’s axes. The transference weight moment of inertia (It), is defined as theweight of the item times the square of the distance from the item's center of gravity to the ship’scenter of gravity. The weight moment of inertia for a surface ship is determined relative to itsown center of gravity in a specified loading condition, normally full load. For submarines, theweight moment of inertia is calculated relative to the submarine’s center of gravity in either aspecified submerged or surfaced loading condition.

8.1 .1 Weight Moment of Inertia

The weight moment of inertia consists of the summation of the transference inertia (It)and item inertia (Io). For further details with regard to estimating weight moment ofinertia/gyradius values about the three rotational axes, see Reference [7].

8.1.2 Gyradius

The gyradius (K) is calculated about the three rotational axes: roll, pitch and yaw.Mathematically, ∆

IK = by definition. Where I is the weight moment of inertia about aparticular axis and ∆ is the total displacement (weight) of the ship.

8.1.3 Gyradius Estimated Values

In early stages of a ship design the weight estimates lacks sufficient detail to estimate or projectgyradii values. Therefore, estimating the gyradii values using the “rules of thumb” method is anacceptable approach. Reference [30] documents the methodology used in estimating andprojecting gyradii values. Table 6, below, is provided as guidance in the selection of theappropriate gyradii values for surface ships and submarines. These values correlate with the“rules of thumb” method, but reflect the ship types and type of hull form. Also, the values areexpressed in terms of a tolerance (+/-) based on a one standard deviation of the ship datastudied.

Table 6. Estimated Gyradius Values for Surface Ships and Submarines

• SURFACE SHIPS ROLL(%B)

PITCH(%L)

YAW(%L)

DDG 51 38.9% 25.2% 25.1%ARS 52 36.5% 25.1% 24.9%FFG 60 36.2% 24.4% 24.3%CG 62 40.4% 25.3% 25.2%MCM 1 38.1% 24.3% 24.4%LHD 2 42.0% 25.6% 25.6%CVN 73 40.9% 23.2% 23.4%LPD 17 40.5% 23.8% 23.8%

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MEAN, CONVENTIONALHULLS FORMS

38.9% 24.7% 24.7%

TOLERANCES (+/-) 2.1% 0.8% 0.7%

TAGOS 19 43.3% 30.5% 32.8%TAGOS 23 43.6% 27.7% 29.4%LCAC 24 29.1% 23.9% 27.5%

MEAN, UNCONVENTIONALHULLS FORMS

39.9% 28.3% 30.7%

TOLERANCES (+/-) 7.2% 3.3% 2.7%

MEAN, SURFACE SHIPS 39.2% 25.8% 26.5%TOLERANCES (+/-) 4.0% 2.5% 3.3%

• SUBMARINES ROLL(%B)

PITCH(%L)

YAW(%L)

LSV NSURFACE 37.4% 22.9% 22.9%SSN 756 NSURFACE 36.4% 24.0% 23.9%SSBN 737 NSURFACE 36.7% 24.3% 24.2%SSN 756 NSUBMERGES 34.7% 25.7% 25.7%SSBN 737 NSUBMERGES 34.9% 26.3% 26.3%

MEAN, SUBMARINES 36.0% 24.6% 24.6%TOLERANCES (+/-) 1.2% 1.4% 1.4%

“RULE OF THUMB” 40.0% 25.0% 25.0%

8.2 Longitudinal Weight Distribution

One of the byproducts of the weight estimate is a longitudinal weight distribution. Aweight distribution is normally developed for both the ships’ lightship and full load conditions.Each element of weight and its longitudinal center of gravity (LCG) is summed to produce theship’s longitudinal weight distribution. The longitudinal distribution is usually based on the 20station spacing between the ships’ FP and AP or between main transverse bulkheads. Theweight and LCG of each element is calculated in the form of a series of trapezoids or rectanglesand summarized as a weight curve for lightship and full load condition. The weight distributioncurve is a graphic representation of the weight of the ship plotted as ton per foot (or any otherdesired units) on a vertical scale versus the length of the ship on a horizontal scale. Figures 6and 7 represent a recent study of longitudinal weight distribution of ships of varying classes andtypes. The vertical scale represented in Figures 6 and 7 indicate the percentage of weight at eachstation for lightship and full load condition, respectively. At various stations there are some widevariances between the ship types based on configuration; however, it is believed that the datarepresented in these plots can be of some value to the naval architect or weight engineer indeveloping an early stage design weight distribution for the purpose of structural hogging andsagging calculations.

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The weight of lightship and full load condition of the ships used in this study are asfollows:

Table 7: Lightship and Full Load ConditionsShip Lightship (LTons) Full Load Cond. (LTons)

MHC 51 827.0 874.6DDG 65 6855.6 8797.2LSD 50 11502.6 16317.0LPD 17 17219.4 25073.8LHD 2 28026.6 40420.1

TAO DH 204 15916.9 40461.1

Figure 6: Lightship 22-Station Weight Distribution

8-5

Figure 7 Full Load Condition 22-Station Weight Distribution

9-1

9.0 REFERENCES

1. Standard Practice for Use of SI (Metric) Units in Maritime Applications, ASTM,No. F133293.

2. Weight Control of Naval Ships, presented at the Society of Naval Architects and MarineEngineers’ Annual Meeting, in New York City, in November 1965; republished byNAVSEA, No. S9096-AA-WCM-010/(U)WT CNTRL, February 1985.

3. Principles of Naval Architecture, SNAME, Volume 1, Stability and Strength, 1988.

4. Weight Control Technical Requirements for Surface Ships, Society of Allied WeightEngineers, Recommended Practice Number 12, Revision Issue No. B., May 21, 1997.

5. Standard Guided for Weight Control Technical Requirements for Surface Ships, ASTM,No. F1808-97, December 1997.

6. Policy for Weight and Vertical Center of Gravity Above Bottom of Keel (KG) Margin forSurface Ships, NAVSEAINST 9096.6B, Approval pending.

7. Standard Coordinate System for Reporting Mass Properties of Surface Ships andSubmarines, Society of Allied Weight Engineers, Recommended Practice No. 13,

June 5, 1996.

8. Expanded Ship Work Breakdown Structure for all Ships and Ship/Combat Systems,NAVSEA, S9040-AA-IDX-010/SWBS 5D and S9040-AA-IDX-020/SWBS 5D (Volumes Iand II), February 1985.

9. Maritime Administration Classification of Merchant Ship Weights, MARAD, Department ofTransportation, January 1985.

10. Weight Classification for U.S. Navy Small Craft, NAVSEA S9009-AB-GTP-010, Naval ShipEngineering Center – Norfolk Division, 1978.

11. Staton, R. N. Ed, Introduction to Aircraft Weight Engineering, Society of Allied WeightEngineers, 1996.

12. Weight Engineers Handbook, Society of Allied Weight Engineers, 1986.

13. Shamburger, C. J., Training of Mass Properties Engineers, Society of Allied WeightEngineers, Paper No. 1655, 1985

14. Hogg, W.A.G., Cimino, D. Methodology to Qualify and Quantify Preliminary Ship DesignWeight Estimates, Society of Allied Weight Engineers, Paper No. 1192, 1977.

15. Straubinger, E.K., Curran, W.C., and Fighera, V.L., Fundamentals of Naval Surface ShipWeight Estimating, Society of Allied Weight Engineers, Paper No. 1533, 1983.

16. Aasen, R., SHIPWEIGHT : a Windows Program for Estimation for Estimation of ShipWeights, Society of Allied Weight Engineers, Paper No. 2441, 1998

17. Ray, D., and Filiopoulis, C., Total Ship Weight Management Computer Program for Today’sand Tomorrow’s Application, Society of Allied Weight Engineers, Paper No. 2466, 1999.

9-2

18. Redmond, M.A., Ship Weight Estimates using Computerized Ratiocination, Society of AlliedWeight Engineers, Paper No. 1602, 1984.

19. Robbins II, J.F., Destroyer Synthesis Computer Algorithm (DESCA), Society of AlliedWeight Engineers, Paper No. 1537, 1983.

20. Orton, P.C., Royal Navy Surface Ship Weight Division, Society of Allied Weight Engineers,Paper No. 1238, 1978.

21. Scott, P.W. and Novelli, J. L., Derivation of a Fuselage Weight Estimating Relationship,“Weight Engineering,” Journal of the Society of Allied Weight Engineers, Fall 1989.

22. Johnsen, I., Hagen, E., Boberg, B., Parametric Study of Steel Weight of Large Oil Tankers,Offshore Technology Conference, Paper No. 1491, 1971.

23. Lamb, T., Merchant Ship Weight Estimation, Society of Allied Weight Engineers, Paper No.860, 1970.

24. Penny, P.W., Riiser, R.M., Preliminary Design of Semi-Submersibles, North East CoastInstitute of Engineers & Shipbuilders, Volume 101-2, March 1986

25. Watson, D.G.M., Gilfillan, A. W., Some Ship Design Methods, Royal Institute of NavalArchitects, London, Transactions, 1977.

26. Schneekluth, H., Ship Design for Efficiency and Economy, Butterworth & Co. Ltd., ISBN 0-408-02790-8, 1987.

27. Kern, P.H., A Statistical Approach to Naval Ship Weight Estimating, Society of AlliedWeight Engineers, Paper No. 1237, 1978

28. Cimino, D., Filiopoulos, C., Weight and KG Margin Analysis of Naval Surface Ships, Societyof Allied Weight Engineers, Paper No. 2356, 19 May 1997.

29. Standard Guide for Conducting a Stability Test (Lightship Survey and Inclining Experiment)to Determine the Light Ship Displacement and Center of Gravity of a Vessel, ASTM,No. F1321-92, February 1993.

30. Cimino, D., Redmond, M, Naval Ships’ Weight Moment of Inertia ( A ComparativeAnalysis), Society of Allied Weight Engineers, Paper No. 2013, 20 May 1991.

See also:• Ferreiro, L.D. and Stonehouse, M. H., A Comparative Study of US and UK Frigate Design.

Society of Naval Architects and Marine Engineers, Transactions, Vol. 99, 1991.

• Mandatory Procedures for Major Defense Acquisition Programs and Major AutomatedInformation System Acquisition Programs, Department of Defense Regulation No. 5000.2-R,15 March 1996.

• Munro-Smith, R., Merchant Ship Types, Institute of Marine Engineers & Marine MediaManagement, London, 1975.

• Naval Ships’ Technical Manual - Chapter 096 - Weights and Stability, NAVSEA, S09086-C6-STM-010/CH-096 R1, 2 August 1996.

9-3

• Petroleum and Natural Gas Industries – Offshore Structures – Weight Control DuringEngineering and Construction, International Standards Organization, No. ISO/WD 15140.8,Draft Standard, February 1998.

• Powell, S. C., Estimation of Machinery Weights, Society of Naval Architects and MarineEngineers, New England Section paper, 1958.

• Standard Guide Listing Relevant Standards and Publications for Commercial Shipbuilding,ASTM F 1547-99.

• T&R Bulletin 7-1, Two Model Weight Control Plan for Ships Accepted Weight Estimates,Society of Naval Architects and Marine Engineers, November 1986.

APPENDIX A

ESWBS 1-DIGIT AND 3-DIGIT LISTING

Appendix A-1

EXPANDED SHIP WORK BREAKDOWN STRUCTURE (ESWBS) THREE DIGIT SUMMARIES

ESWBS TITLE

1 GROUP 1 HULL STRUCTURE

100 HULL STRUCTURE, GENERAL

110 SHELL AND SUPPORTING STRUCTURE

111 SHELL PLATING, SURFACE SHIP AND SUBMARINE PRESSURE HULL

112 SHELL PLATING, SUBMARINE NONPRESSURE HULL113 INNER BOTTOM

114 SHELL APPENDAGES

115 STANCHIONS116 LONGIT. FRAMING, SURF SHIP AND SUBMARINE PRESSURE HULL

117 TRANSV. FRAMING, SURFACE SHIP AND SUBMARINE PRESSURE HULL

118 LONGITUDINAL AND TRANSVERSE SUBMARINE NONPRESSURE HULL119 LIFT SYSTEM FLEXIBLE SKIRTS AND SEALS

120 HULL STRUCTURAL BULKHEADS

121 LONGITUDINAL STRUCTURAL BULKHEADS122 TRANSVERSE STRUCTURAL BULKHEADS

123 TRUNKS AND ENCLOSURES

124 BULKHEADS IN TORPEDO PROTECTION SYSTEM125 SUBMARINE HARD TANKS

126 SUBMARINE SOFT TANKS

130 HULL DECKS131 MAIN DECK

132 2ND DECK

133 3RD DECK134 4TH DECK

135 5TH DECK AND DECKS BELOW

136 01 HULL DECK (FORECASTLE AND POOP DECKS)137 02 HULL DECK

138 03 HULL DECK

139 04 HULL DECK AND HULL DECKS ABOVE140 HULL PLATFORMS AND FLATS

141 1ST PLATFORM

142 2ND PLATFORM143 3RD PLATFORM

144 4TH PLATFORM

145 5TH PLATFORM149 FLATS

150 DECK HOUSE STRUCTURE

151 DECKHOUSE STRUCTURE TO FIRST LEVEL152 1ST DECKHOUSE LEVEL

153 2ND DECKHOUSE LEVEL

154 3RD DECKHOUSE LEVEL155 4TH DECKHOUSE LEVEL

156 5TH DECKHOUSE LEVEL

157 6TH DECKHOUSE LEVEL158 7TH DECKHOUSE LEVEL

159 8TH DECKHOUSE LEVEL AND ABOVE

160 SPECIAL STRUCTURES161 STRUCTURAL CASTINGS, FORGINGS, AND EQUIV. WELDMENTS

163 SEA CHESTS

164 BALLISTIC PLATING

Appendix A-2

ESWBS TITLE

165 SONAR DOMES

166 SPONSONS

167 HULL STRUCTURAL CLOSURES168 DECKHOUSE STRUCTURAL CLOSURES

169 SPECIAL PURPOSE CLOSURES AND STRUCTURES

170 MASTS, KINGPOSTS, AND SERVICE PLATFORMS171 MASTS, TOWERS, TETRAPODS

172 KINGPOSTS AND SUPPORT FRAMES

179 SERVICE PLATFORMS180 FOUNDATIONS

181 HULL STRUCTURE FOUNDATIONS

182 PROPULSION PLANT FOUNDATIONS183 ELECTRIC PLANT FOUNDATIONS

184 COMMAND AND SURVEILLANCE FOUNDATIONS

185 AUXILIARY SYSTEMS FOUNDATIONS186 OUTFIT AND FURNISHINGS FOUNDATIONS

187 ARMAMENT FOUNDATIONS

190 SPECIAL PURPOSE SYSTEMS191 BALLAST, FIXED OR FLUID, AND BUOYANCY UNITS

192 COMPARTMENT TESTING

195 ERECTION OF SUB SECTIONS (PROGRESS REPORT ONLY)198 FREE FLOODING LIQUIDS

199 HULL REPAIR PARTS AND SPECIAL TOOLS

2 GROUP 2 PROPULSION PLANT200 PROPULSION PLANT, GENERAL

210 ENERGY GENERATING SYSTEMS (NUCLEAR)

211 (RESERVED)212 NUCLEAR STEAM GENERATOR

213 REACTORS

214 REACTOR COOLANT SYSTEM215 REACTOR COOLANT SERVICE SYSTEMS

216 REACTOR PLANT AUXILIARY SYSTEMS

217 NUCLEAR POWER CONTROL AND INSTRUMENTATION218 RADIATION SHIELDING (PRIMARY)

219 RADIATION SHIELDING (SECONDARY)

220 ENERGY GENERATING SYSTEMS (NONNUCLEAR)221 PROPULSION BOILERS

222 GAS GENERATORS

223 MAIN PROPULSION BATTERIES224 MAIN PROPULSION FUEL CELLS

230 PROPULSION UNITS

231 PROPULSION STEAM TURBINES232 PROPULSION STEAM ENGINES

233 PROPULSION INTERNAL COMBUSTION ENGINES

234 PROPULSION GAS TURBINES235 ELECTRIC PROPULSION

236 SELFCONTAINED PROPULSION SYSTEMS

237 AUXILIARY PROPULSION DEVICES238 SECONDARY PROPULSION

239 EMERGENCY PROPULSION

240 TRANSMISSION AND PROPULSOR SYSTEMS241 PROPULSION REDUCTION GEARS

242 PROPULSION CLUTCHES AND COUPLINGS

Appendix A-3

ESWBS TITLE

243 PROPULSION SHAFTING

244 PROPULSION SHAFT BEARINGS

245 PROPULSORS246 PROPULSOR SHROUDS AND DUCTS

247 WATER JET PROPULSORS

248 LIFT SYSTEM FANS AND DUCTING250 PROPULSION SUPPORT SYSTEMS (EXCEPT FUEL/LUBE)

251 COMBUSTION AIR SYSTEM

252 PROPULSION CONTROL SYSTEM253 MAIN STEAM PIPING SYSTEM

254 CONDENSERS AND AIR EJECTORS

255 FEED AND CONDENSATE SYSTEM256 CIRCULATING AND COOLING SEA WATER SYSTEM

257 RESERVE FEED AND TRANSFER SYSTEM

258 HP STEAM DRAIN SYSTEM259 UPTAKES (INNER CASING)

260 PROPULSION SUPPORT SYSTEMS (FUEL AND LUBE OIL)

261 FUEL SERVICE SYSTEM262 MAIN PROPULSION LUBE OIL SYSTEM

263 SHAFT LUBE OIL SYSTEM (SUBMARINES)

264 LUBE OIL FILL, TRANSFER, AND PURIFICATION290 SPECIAL PURPOSE SYSTEMS

298 PROPULSION PLANT OPERATING FLUIDS

299 PROPULSION PLANT REPAIR PARTS AND SPECIAL TOOLS3 GROUP 3 ELECTRIC PLANT

300 ELECTRIC PLANT, GENERAL

310 ELECTRIC POWER GENERATION311 SHIP SERVICE POWER GENERATION

312 EMERGENCY GENERATORS

313 BATTERIES AND SERVICE FACILITIES314 POWER CONVERSION EQUIPMENT

320 POWER DISTRIBUTION SYSTEMS

321 SHIP SERVICE POWER CABLE322 EMERGENCY POWER CABLE SYSTEM

323 CASUALTY POWER CABLE SYSTEM

324 SWITCHGEAR AND PANELS325 ARC FAULT DETECTOR (AFD) SYSTEMS

330 LIGHTING SYSTEM

331 LIGHTING DISTRIBUTION332 LIGHTING FIXTURES

340 POWER GENERATION SUPPORT SYSTEMS

341 SSTG LUBE OIL342 DIESEL SUPPORT SYSTEMS

343 TURBINE SUPPORT SYSTEMS

390 SPECIAL PURPOSE SYSTEMS398 ELECTRIC PLANT OPERATING FLUIDS

399 ELECTRIC PLANT REPAIR PARTS AND SPECIAL TOOLS

4 GROUP 4 COMMAND & SURVEILLANCE400 COMMAND AND SURVEILLANCE, GENERAL

410 COMMAND AND CONTROL SYSTEMS

411 DATA DISPLAY GROUP412 DATA PROCESSING GROUP

413 DIGITAL DATA SWITCHBOARDS

Appendix A-4

ESWBS TITLE

414 INTERFACE EQUIPMENT

415 DIGITAL DATA COMMUNICATIONS

417 COMMAND AND CONTROL ANALOG SWITCHBOARDS420 NAVIGATION SYSTEMS

421 NONELECTRICAL/NONELECTRONIC NAVIGATION AIDS

422 ELECTRICAL NAVIGATION AIDS (INCL NAVIG. LIGHTS)423 ELECTRONIC NAVIGATION SYSTEMS

424 ELECTRONIC NAVIGATION SYSTEMS, ACOUSTICAL

425 PERISCOPES426 ELECTRICAL NAVIGATION SYSTEMS

427 INERTIAL NAVIGATION SYSTEMS

428 NAVIGATION CONTROL MONITORING430 INTERIOR COMMUNICATIONS

431 SWITCHBOARDS FOR INTERIOR COMMUNICATION SYSTEMS

432 TELEPHONE SYSTEMS433 ANNOUNCING SYSTEMS

434 ENTERTAINMENT AND TRAINING SYSTEMS

435 VOICE TUBES AND MESSAGE PASSING SYSTEMS436 ALARM, SAFETY, AND WARNING SYSTEMS

437 INDICATING, ORDER, AND METERING SYSTEMS

438 CONSOLIDATED CONTROL AND DISPLAY SYSTEMS439 RECORDING AND TELEVISION SYSTEMS

440 EXTERIOR COMMUNICATIONS

441 RADIO SYSTEMS442 UNDERWATER SYSTEMS

443 VISUAL AND AUDIBLE COMMUNICATION SYSTEMS

444 TELEMETRY SYSTEMS445 TELETYPE AND FACSIMILE SYSTEMS

446 SECURITY EQUIPMENT SYSTEMS

450 SURVEILLANCE SYSTEMS, SURFACE AND AIR451 SURFACE SURVEILLANCE RADAR SYSTEMS

452 2D AIR RADAR SYSTEMS

453 3D AIR RADAR SYSTEMS454 AIRCRAFT CONTROL RADAR SYSTEMS

455 IDENTIFICATION SYSTEMS

456 MULTIFUNCTION RADAR SYSTEMS457 INFRARED SURVEILLANCE AND TRACKING SYSTEMS

458 AUTOMATIC DETECTION AND TRACKING SYSTEMS

459 SPACE VEHICLE ELECTRONIC TRACKING460 SURVEILLANCE SYSTEMS (UNDERWATER)

461 ACTIVE SURVEILLANCE SONAR

462 PASSIVE SURVEILLANCE SONAR463 MULTIPLE MODE SURVEILLANCE SONAR

464 ACOUSTIC ANALYSIS SYSTEMS

465 BATHYTHERMOGRAPH466 AIRBORNE MULTIPURPOSE SHIP EQUIPMENT SYSTEMS

468 SURFACE SHIP COMBAT SYSTEMS

469 SUBMARINE COMBAT SYSTEMS470 COUNTERMEASURE SYSTEMS

471 ACTIVE EW (INCL COMBINATION ACTIVE/PASSIVE)

472 PASSIVE ECM473 UNDERWATER COUNTERMEASURES

474 DECOY SYSTEMS

Appendix A-5

ESWBS TITLE

475 DEGAUSSING SYSTEMS

476 MINE COUNTERMEASURE SYSTEMS

480 FIRE CONTROL SYSTEMS481 GUN FIRE CONTROL SYSTEMS

482 MISSILE FIRE CONTROL SYSTEMS

483 UNDERWATER FIRE CONTROL SYSTEMS484 INTEGRATED FIRE CONTROL SYSTEMS

489 WEAPON SYSTEMS SWITCHBOARDS

490 SPECIAL PURPOSE SYSTEMS491 ELECTRONIC TEST, CHECKOUT, AND MONITORING EQUIPMENT

492 FLIGHT CONTROL AND INSTRUMENT LANDING SYSTEMS

493 AUTOMATED DATA PROCESSING SYSTEMS (NONCOMBAT)494 METEOROLOGICAL SYSTEMS

495 SPECIAL PURPOSE INTELLIGENCE SYSTEMS

498 COMMAND AND SURVEILLANCE OPERATING FLUIDS499 COMMAND AND SURV. REPAIR PARTS AND SPECIAL TOOLS

5 GROUP 5 AUXILIARY SYSTEMS500 AUXILIARY SYSTEMS, GENERAL510 CLIMATE CONTROL

511 COMPARTMENT HEATING SYSTEM

512 VENTILATION SYSTEM513 MACHINERY SPACE VENTILATION SYSTEM

514 AIR CONDITIONING SYSTEM

515 AIR REVITALIZATION SYSTEMS (SUBMARINES)516 REFRIGERATION SYSTEM

517 AUXILIARY BOILERS AND OTHER HEAT SOURCES

520 SEA WATER SYSTEMS521 FIREMAIN AND FLUSHING (SEA WATER) SYSTEM

522 SPRINKLER SYSTEM

523 WASHDOWN SYSTEM524 AUXILIARY SEA WATER SYSTEM

526 SCUPPERS AND DECK DRAINS

527 FIREMAIN ACTUATED SERVICES OTHER528 PLUMBING DRAINAGE

529 DRAINAGE AND BALLASTING SYSTEM

530 FRESH WATER SYSTEMS531 DISTILLING PLANT

532 COOLING WATER

533 POTABLE WATER534 AUXILIARY STEAM AND DRAINS WITHIN MACHINERY BOX

535 AUXILIARY STEAM AND DRAINS OUTSIDE MACHINERY BOX

536 AUXILIARY FRESH WATER COOLING540 FUELS AND LUBRICANTS, HANDLING AND STORAGE

541 SHIP FUEL AND FUEL COMPENSATING SYSTEM

542 AVIATION AND GENERAL PURPOSE FUELS543 AVIATION AND GENERAL PURPOSE LUBRICATING OIL

544 LIQUID CARGO

545 TANK HEATING546 AUXILIARY LUBRICATION SYSTEMS

549 SPECIAL FUEL AND LUBRICANTS, HANDLING AND STOWAGE

550 AIR, GAS, AND MISCELLANEOUS FLUID SYSTEMS551 COMPRESSED AIR SYSTEMS

552 COMPRESSED GASES

Appendix A-6

ESWBS TITLE

553 O2 N2 SYSTEM

554 MAIN BALLAST TANK BLOW AND LIST CONTROL SYSTEM

555 FIRE EXTINGUISHING SYSTEMS556 HYDRAULIC FLUID SYSTEM

557 LIQUID GASES, CARGO

558 SPECIAL PIPING SYSTEMS560 SHIP CONTROL SYSTEMS

561 STEERING AND DIVING CONTROL SYSTEMS

562 RUDDER563 HOVERING AND DEPTH CONTROL (SUBMARINE)

564 TRIM AND DRAIN SYSTEMS (SUBMARINES)

565 TRIM AND HEEL SYSTEMS (SURFACE SHIPS)566 DIVING PLANES AND STABILIZING FINS (SUBMARINES)

567 STRUT AND FOIL SYSTEMS

568 MANEUVERING SYSTEMS570 REPLENISHMENT SYSTEMS

571 REPLENISHMENTATSEA SYSTEMS

572 SHIP STORES AND EQUIPMENT HANDLING SYSTEMS573 CARGO HANDLING SYSTEMS

574 VERTICAL REPLENISHMENT SYSTEMS

575 VEHICLE HANDLING AND STOWAGE SYSTEMS580 MECHANICAL HANDLING SYSTEMS

581 ANCHOR HANDLING AND STOWAGE SYSTEMS

582 MOORING AND TOWING SYSTEMS583 BOATS, BOAT HANDLING AND STOWAGE SYSTEMS

584 LANDING CRAFT HANDLING AND STOWAGE SYSTEMS

585 ELEVATING AND RETRACTING GEAR586 AIRCRAFT RECOVERY SUPPORT SYSTEMS

587 AIRCRAFT LAUNCH SUPPORT SYSTEMS

588 AIRCRAFT HANDLING, SERVICING AND STOWAGE589 MISCELLANEOUS MECHANICAL HANDLING SYSTEMS

590 SPECIAL PURPOSE SYSTEMS

591 SCIENTIFIC AND OCEAN ENGINEERING SYSTEMS592 SWIMMER AND DIVER SUPPORT AND PROTECTION SYSTEMS

593 ENVIRONMENTAL POLLUTION CONTROL SYSTEMS

594 SUBMARINE RESCUE, SALVAGE, AND SURVIVAL SYSTEMS595 TOWING, LAUNCHING AND HANDLING FOR UNDERWATER SYS.

596 HANDLING SYS. FOR DIVER AND SUBMERSIBLE VEHICLES

597 SALVAGE SUPPORT SYSTEMS598 AUXILIARY SYSTEMS OPERATING FLUIDS

599 AUXILIARY SYSTEMS REPAIR PARTS AND TOOLS

6 GROUP 6 OUTFIT & FURNISHINGS600 OUTFIT AND FURNISHINGS, GENERAL

610 SHIP FITTINGS

611 HULL FITTINGS612 RAILS, STANCHIONS, AND LIFELINES

613 RIGGING AND CANVAS

620 HULL COMPARTMENTATION621 NONSTRUCTURAL BULKHEADS

622 FLOOR PLATES AND GRATINGS

623 LADDERS624 NONSTRUCTURAL CLOSURES

625 AIRPORTS, FIXED PORTLIGHTS, AND WINDOWS

Appendix A-7

ESWBS TITLE

630 PRESERVATIVES AND COVERINGS

631 PAINTING

632 ZINC AND METALLIC COATINGS633 CATHODIC PROTECTION

634 DECK COVERING

635 HULL INSULATION636 HULL DAMPING

637 SHEATHING

638 REFRIGERATED SPACES639 RADIATION SHIELDING

640 LIVING SPACES

641 OFFICER BERTHING AND MESSING SPACES642 NONCOMMISSIONED OFFICER BERTHING AND MESSING SPACES

643 ENLISTED PERSONNEL BERTHING AND MESSING SPACES

644 SANITARY SPACES AND FIXTURES645 LEISURE AND COMMUNITY SPACES

650 SERVICE SPACES

651 COMMISSARY SPACES652 MEDICAL SPACES

653 DENTAL SPACES

654 UTILITY SPACES655 LAUNDRY SPACES

656 TRASH DISPOSAL SPACES

660 WORKING SPACES661 OFFICES

662 MACHINERY CONTROL CENTERS FURNISHINGS

663 ELECTRONICS CONTROL CENTERS FURNISHINGS664 DAMAGE CONTROL STATIONS

665 WORKSHOPS, LABS, TEST AREAS (INCL PORTABLE TOOLS, EQUIP)

670 STOWAGE SPACES671 LOCKERS AND SPECIAL STOWAGE

672 STOREROOMS AND ISSUE ROOMS

673 CARGO STOWAGE690 SPECIAL PURPOSE SYSTEMS

691 TRANSMISSION LOSS TREATMENT

698 OUTFIT AND FURNISHINGS OPERATING FLUIDS699 OUTFIT AND FURNISH. REPAIR PARTS AND SPECIAL TOOLS

7 GROUP 7 ARMAMENT700 ARMAMENT, GENERAL710 GUNS AND AMMUNITION

711 GUNS

712 AMMUNITION HANDLING713 AMMUNITION STOWAGE

720 MISSILES AND ROCKETS

721 LAUNCHING DEVICES (MISSILES AND ROCKETS)722 MISSILE, ROCKET, AND GUIDANCE CAPSULE HANDLING SYS.

723 MISSILE AND ROCKET STOWAGE

724 MISSILE HYDRAULICS725 MISSILE GAS

726 MISSILE COMPENSATING

727 MISSILE LAUNCHER CONTROL728 MISSILE HEATING, COOLING, TEMPERATURE CONTROL

729 MISSILE MONITORING, TEST AND ALIGNMENT

Appendix A-8

ESWBS TITLE

730 MINES

731 MINE LAUNCHING DEVICES

732 MINE HANDLING733 MINE STOWAGE

740 DEPTH CHARGES

741 DEPTH CHARGE LAUNCHING DEVICES742 DEPTH CHARGE HANDLING

743 DEPTH CHARGE STOWAGE

750 TORPEDOES751 TORPEDO TUBES

752 TORPEDO HANDLING

753 TORPEDO STOWAGE754 SUBMARINE TORPEDO EJECTION

755 TORPEDO SUPPORT, TEST AND ALIGNMENT

760 SMALL ARMS AND PYROTECHNICS761 SMALL ARMS AND PYROTECHNIC LAUNCHING DEVICES

762 SMALL ARMS AND PYROTECHNIC HANDLING

763 SMALL ARMS AND PYROTECHNIC STOWAGE770 CARGO MUNITIONS

772 CARGO MUNITIONS HANDLING

773 CARGO MUNITIONS STOWAGE780 AIRCRAFT RELATED WEAPONS

782 AIRCRAFT RELATED WEAPONS HANDLING

783 AIRCRAFT RELATED WEAPONS STOWAGE784 AIRCRAFT RELATED WEAPONS ELEVATORS, UPPER STAGES

785 AIRCRAFT RELATED WEAPONS ELEVATORS, LOWER STAGES

786 AIRCRAFT RELATED WEAPONS, HYDRAULICS790 SPECIAL PURPOSE SYSTEMS

792 SPECIAL WEAPONS HANDLING

793 SPECIAL WEAPONS STOWAGE797 MISCELLANEOUS ORDNANCE SPACES

798 ARMAMENT OPERATING FLUIDS

799 ARMAMENT REPAIR PARTS AND SPECIAL TOOLS

F GROUP F FULL LOAD, LOADSF00 LOADS (FULL LOAD CONDITION)F10 SHIPS FORCE, AMPHIB. FORCE, TROOPS AND PASSENGERS

F11 SHIPS OFFICERS

F12 SHIPS NONCOMMISSIONED OFFICERSF13 SHIPS ENLISTED MEN

F14 MARINES

F15 TROOPSF16 AIR WING PERSONNEL

F19 OTHER PERSONNEL

F20 MISSION RELATED EXPENDABLES AND SYSTEMS F21 SHIP AMMUNITION (FOR USE BY SHIP ON WHICH STOWED)

F22 ORDNANCE DELIVERY SYSTEMS AMMUNITION

F23 ORDNANCE DELIVERY SYSTEMSF24 ORDNANCE REPAIR PARTS (SHIP AMMO)

F25 ORDNANCE REPAIR PARTS (ORDNANCE DELIVERY SYS. AMMO)

F26 ORDNANCE DELIVERY SYSTEMS SUPPORT EQUIPMENTF29 SPECIAL MISSION RELATED SYSTEMS AND EXPENDABLES

Appendix A-9

ESWBS TITLE

F30 STORES

F31 PROVISIONS AND PERSONNEL STORES

F32 GENERAL STORESF33 MARINES STORES (FOR SHIP'S COMPLEMENT)

F39 SPECIAL STORES

F40 FUELS AND LUBRICANTSF41 DIESEL FUEL

F42 JP5

F43 GASOLINEF44 DISTILLATE FUEL

F45 NAVY STANDARD FUEL OIL (NSFO)

F46 LUBRICATING OILF49 SPECIAL FUELS AND LUBRICANTS

F50 LIQUIDS AND GASES (NON FUEL TYPE)

F51 SEA WATERF52 FRESH WATER

F53 RESERVE FEED WATER

F54 HYDRAULIC FLUIDF55 SANITARY TANK LIQUID

F56 GAS (NON FUEL TYPE)

F59 MISCELLANEOUS LIQUIDS (NON FUEL TYPE)F60 CARGO

F61 CARGO, ORDNANCE AND ORDNANCE DELIVERY SYSTEMS

F62 CARGO, STORESF63 CARGO, FUELS AND LUBRICANTS

F64 CARGO, LIQUIDS (NON FUEL TYPE)

F65 CARGO, CRYOGENIC AND LIQUIFIED GASF66 CARGO, AMPHIBIOUS ASSAULT SYSTEMS

F67 CARGO, GASES

F69 CARGO, MISCELLANEOUSF70 SEA WATER BALLAST (SUBMARINES)

F71 MAIN BALLAST WATER (SUBMARINES)

F72 VARIABLE BALLAST WATER (SUBMARINES)F73 RESIDUAL WATER (SUBMARINES)

M GROUP M ACQUISITION MARGINSM00 MARGINS

M10 CONTRACTOR CONTROLLED MARGINS

M11 DESIGN AND BUILDING MARGINM12 BUILDING MARGIN (RESERVED)

M20 GOVERNMENT CONTROLLED MARGIN (SURFACE SHIP)

M21 PRELIMINARY DESIGN MARGIN (SURFACE SHIP)M22 CONTRACT DESIGN MARGIN (SURFACE SHIP)

M23 CONTRACT MODIFICATION MARGIN (SURFACE SHIP)

M24 GEM MARGIN (SURFACE SHIP)M25 FUTURE GROWTH MARGIN (SURFACE SHIP)

M26 SERVICE LIFE MARGIN (SURFACE SHIP)

M27 NUCLEAR MACHINERY MARGIN (SURFACE SHIP)M30 GOVERNMENT CONTROLLED MARGIN STATUS (SUBMARINES)

M31 PRELIMINARY DESIGN MARGIN (SUBMARINE)

M32 CONTRACT DESIGN MARGIN (SUBMARINE)M33 NAVSHIPS DEVELOPMENT MARGIN (SUBMARINE)

M34 NUCLEAR MACHINERY MARGIN (SUBMARINE)

Appendix A-10

ESWBS TITLE

M35 FUTURE GROWTH MARGIN (SUBMARINE)

M36 STABILITY LEAD STATUS (SUBMARINE)

M37 TRIMMING LEAD STATUS (SUBMARINE)M40 BALLAST STATUS (SUBMARINE)

M41 LEAD, INTERNAL (SUBMARINE)

M42 LEAD, EXTERNAL (SUBMARINE)M43 LEAD, MET (SUBMARINE)

M44 STEEL, INTERNAL (SUBMARINE)

M45 STEEL, EXTERNAL (SUBMARINE)M46 STEEL, MBT (SUBMARINE)

M47 LEAD CORRECTION, MET (SUBMARINE)

M48 LEAD CORRECTION, OTHER THEN MET (SUBMARINE)

APPENDIX B

MARAD WEIGHT CLASSIFICATION LISTING

Appendix B-1

HULL STRUCTURE (Group 0-9)CODE ITEM CODE ITEM

0-0 Stem casting 5-0 Pillars and Girders

1 Stern frame casting 1

2 Boss casting 2

3 Shaft struts 3

4 Misc. Hull Castings 4

5 5

6 6

7 7

8 8

9 9

Forgings and Castings Pillars and Girders

1-0 Flat Plate keel 6-0 Inner Bottom Plating

1 Shell plating 1 Platform Deck

2 Bulwarks 2 Sponsons

3 Bilge keels 3 Cantilevers

4 Boss plating 4 Cofferdam Flats & Floors

5 Rubbing strips and fenders 5 Helicopter Platform

6 Sea Chests / Skin coolers 6 Miscel laneous Flats and Floors

7 Skegs 7 Stability Column Support Legs

8 Thruster Tunnels / Wells 8 Protective Covers / Barriers

9 9

Shell Plating Hull Miscellaneous

2-0 Center vertical keel 7-0 Main Engine Foundations

1 Trans. framing in 1.B. 1 Boiler Foundations

2 Long. framing in 1.B. 2 Auxiliary Machine Foundations

3 Trans. framing outside 1.B. 3 Shaft Stools Foundations

4 Framing in peaks 4 Miscellaneous Foundations

5 Transom and cants 5 Cryogenic / Chemical Foundations

6 Web frames 6

7 Long'l Girder Ring 7

8 Long'l Stringer Ring 8

9 9

Framing Foundations

3-0 8-0

1 1

2 2

3 3

4 4

5 5

6 6

7 7

8 8 Miscellaneous Houses

9 9 Stack Enclosure

Deck Plating and Beams Superstructures

4-0 Main trans. W.T. bhds. SUB TOTAL GROUPS 0 THROUGH 8

1 Trans. W.T. and O.T. bhds 9-0 Riveting and Welding

2 Long. W.T. and O.T. bhds 1 Welding

3 Structural N.W.T. bhds 2 Mill Tolerance

4 Nonstructural bhds 3

5 Trunks structural 4

6 Trunks nonstructural 5

7 Stair enclosures 6

8 Hatch coamings 7

9 Drill Wells / Leg Wells

Bulkheads and Trunks Riveting and Welding

Appendix B-2

OUTFIT (Group 10 – 19)

CODE ITEM CODE ITEM

10-0 Steel Masts, Kingposts , etc. 15-0 Anchors, Chains, Lines

1 Steel Booms 1 Boats and Boat Handling

2 Steel Hatch Covers and Beams 2 Rigging and Blocks

3 Steel Stairways 3 Canvas Work

4 Steel Sheet Metal Work 4 Miscellaneous Deck Outfit

5 Drill Derricks 5 Underwater Support Equipment

6 Self-Unloading Booms 6 Exterior Paint

7 7 Interior Paint

8 8 Tank Paint

9 9 Special Coatings

Structure Steel in Outfit Deck Outfit

11-0 Deck Castings, Mooring Fittings 16-0 Galley and Pantry Equipment

1 Mast and Spar Forgings 1 Utility Space Equipment

2 Rails and Stanchions 2 Steward's Outfit

3 Ladders 3

4 Miscellaneous Hull Fittings 4

5 Ratproofing 5

6 Guide Struc. / Lashings 6

7 Prim. Cryogenic Contain. 7 National Defense

8 Sec. Cryogenic Contain. 8

9 Tug / Barge Connections 9

Hull Attachments Steward's Outfit / Defense

12-0 Sliding W.T. Doors 17-0 Fire Det. and Ext. System

1 Hinged W.T. Doors 1 Heating System

2 Manholes and Scuttles 2 Ventilation Natural

3 Airports, Windows and Lights 3 Ventilation Mechanical

4 Hatches and Ports O.T. or W.T. 4 Refrigerating Systems

5 N.W.T. Steel Doors 5 Plumbing Fixtures and Drains

6 Skylights and Companions 6

7 Movable Ramps 7

Lights, Doors Hatches, Ramps Hull Engineering

13-0 Wooden Masts and Spars 18-0 Bilge and Ballast System

1 Wood Hatch Covers 1 Cargo Oil System

2 Hold Ceiling and Sparring 2 Deck Steam and Ex. System

3 Miscellaneous Carpenter Work 3 Fire Mains

4 Wood Decks 4 San. and Fresh Water System

5 Wood Houses 5 Fuel Oil Transfer System

6 Composition Deck Covering 6 Vents, Sounding and Overflows

7 Sheet / Block Deck Tile 7 Cryogenic / Chem. Cargo Sys.

8 Ceramic / Misc. Deck Tile 8 Inert/ Nitrogen System

9 Cement and Misc. Coverings 9 Hydraulic System

Carpenter Work and Decking Piping

14-0 Interior Joiner Work 19-0 Deck Machinery

1 Furniture 1 Steer. Gear and Rudder

2 2 Communicating System

3 Joiner Decks 3 Electric Plant

4 Decorative Joiner Work 4 Dumb Waiters and Elevators

5 Accommodation Ladder 5 Auxiliary Boiler

6 6 Distiller. Plant (ship use)

7 Special Insulation 7 Stabilizers

8 Insulation in Quarters 8 Thrusters

9 Fire Insulation 9 Bulk Unloading

Joiner Work Miscellaneous Machinery

Appendix B-3

MACHINERY (Group 20-29)CODE ITEM CODE ITEM

20-0 Main Propulsion 26-0 Boilers

1 Turbine Drain and LeakOff System 1 Fuel Oil Burners

2 Main Reduction Gears 2 Soot Blowers

3 Main Condenser 3 Boiler Draft System

4 Main Air Ejector 4 Automatic Combustion Control

5 Main Circulating System 5 Stacks and Uptakes

6 6 F.O. Service System

7 7 LNG Boil Off System

8

Main Propulsion Units Boilers and F.O. System

21-0 Feed Heaters 27-0 Main Steam Piping

1 Feed and Condensate System 1 Auxiliary Steam Piping

2 2 Exhaust and Escape Piping

3 3 Steam Drain System

Feed and Condensate Equip. 4 Whistles

22-0 Makeup Feed System 5

1 Contaminated System 6

2 Salt Water Eva p. System

3 Steam Piping

4 28-0 Access

Evaporator System 1 Work Shop

23-0 Shafting 2 Lifting and Handling Gear

1 Bearings and Stern Tube 3 Machinery Space Ventilation

2 Propellers 4 Machinery Space Fixtures

3 Miscellaneous Shafting Parts 5 Spare Parts

4 Shafting and Propeller Spares 6 Miscellaneous Instruments and Gages

5 7

6 8

Shafting and Propellers Miscellaneous

24-0 Lube. Oil System 29-0 Liquids in Machinery (Gr. 1219)

1 Miscellaneous Engine Oil Tanks 1 Water (Gr. 2028)

2 2 Oil (Gr. 2028)

3 3

Lubricating Oil System 4

25-0 Service Compressed Air Serv. Sys. Liquids in Machinery

1 Starting Air System

2 Scavenger Air System

3

4

Air System

APPENDIX C

INCLINING EXPERIMENT GENERAL GUIDANCE

Appendix C-1

Inclining Experiment General Guidance

The following represents general guidance when planning as well as conducting an incliningexperiment:

• An inclining experiment is the only satisfactory method of accurately determining thelocation of the center of gravity of a ship.6, 7 The following paragraphs relate to actions thatshould be addressed in planning for the experiment:

1.. The accuracy of the inclining experiment is improved when the ship is as nearly completeas practicable, and therefore the inclining experiment should be conducted toward the end ofthe construction period, and in some cases where ship stability is in question, a deadweightsurvey or an inclining experiment is performed prior to any sea trials. Simply stated, the shipshould be as near complete as practicable for the test. In most cases there is a requirement forthe technical office (U.S. Navy, U.S. Coast Guard, American Bureau of Shipping, DNV,Owner, etc.) to officially witness the experiment, therefore the inclining procedure andschedule of events should be submitted for their review at least thirty days prior to the event. 2. A thorough cleaning of the ship should be conducted prior to the experiment. Weightsurveys including estimates of weight and the longitudinal, transverse and vertical center ofgravity locations must be conducted. The survey of (weights to deduct) is to determine theamount of foreign material such as scaffolding, or other construction material that is not part oflightship but may be onboard ship at the time of the inclining experiment. Another survey of(weights to add) is performed to determine all items which are part of the lightship but have notbeen put onboard. Additionally, a survey for items of lightship (weights to relocate) that areonboard but not in their final position must be identified, the moments that will result from therelocation of these items must be recorded. The information from the surveys will be used inthe development of the inclining report. The surveys take advantage of the most accurateweight information available and in some cases require actual weighing of individualcomponents. 3. The ship’s trim and list should be as near to zero as practicable for the test to avoid havingto make adjustments to the tank capacity and curves of form data. It is common practice to useconcrete leveling blocks for this purpose. In addition, care must be exercised in thedetermination of the liquids in tanks and their associated free surface effect on the test. Ideally,tanks should be either completely full or completely empty for the experiment. An empty tankliterally means that the tank is empty. The liquid below the suction has been removed throughwhatever means, this may include actually moping of tanks. Whereas a full tank means that thesounding is above the top of the tank. To prevent air pockets in tanks, air escapes are requiredat the highest point of the tank and heeling of the ship is necessary to assist in the removal ofair while filling the tanks. In general, tanks that must contain liquid should be between 20 and80 percent full, provided that calculations for free-surface effect can be calculated accurately.Additionally, a careful review of the piping systems must be performed to determine cross-connect piping, all valves must be closed to prevent any transfer of liquids.

Appendix C-2

4. Efforts should be made to reduce the number of people aboard during the test, and thoseonboard should stay in an assigned location during the experiment. In addition, doors, cranebooms and boats should be secured to prevent swinging during the experiment. 5. All mooring lines should be well slacked while inclining measurements are being taken,and the gangways, fenders, and construction lines should be clear of the ship. Wind forceseffect the accuracy of the test and it is recommended that should wind forces exceed 10 knots,the test should be delayed until the winds subside. 6. The displacement of the vessel is determined by reading the draft marks, therefore, it isimportant that the installation of the draft marks on the vessel be certified prior to the incliningexperiment. When reading drafts, they should be taken simultaneously from boats located onthe port and starboard sides. Readings are to be taken from the forward, amidships, and afterdraft marks at the time of the inclining. Some shipbuilders have developed a draft readingdevice made up of a clear tube with a hole in the bottom and a scale inside to help dampen outwave action. The U. S. Navy Technical Manual on weights and stability addresses the accuracyof reading drafts as “Draft readings should be taken to the nearest one-quarter of an inch.”6 Theimportance of weight measurement accuracy can be further emphasized by comparing a typicalNavy destroyer’s tons per inch of draft (TPI); whereas, one quarter of an inch equates to over13 tons displacement. A larger ship such as the LHD Wasp Class, the reading to the nearestone-quarter of an inch will equate to over 38 tons displacement. 7. The most common device for measuring the angle of list is a pendulum constructed of afine wire such as piano wire, of sufficient length, with a heavy plumb bob damped in a troughfilled with heavy weight oil. A horizontal batten is attached to each trough for recordingpendulum deflections. Another device, a u-tube made of clear vinyl or plastic and filled withwater affixed to vertical battens is installed transversely port to starboard. When readingmeasurements, it is important to note that the ship should be allowed sufficient time to settle-out after each block movement.

• The following reflects a condensed version of the events of an inclining experiment:

1. The inclining experiment for some shipyards begins around midnight in an attempt to takeadvantage of typically calmer wind and sea conditions. A survey of weights to add, weights todeduct and weights to relocate is needed because it is the nature of ship construction to haveunexpected changes in the day to day condition of the ship. All spaces should be included inthe survey, including voids and spaces reported as empty. All doors and hatches are secured intheir normally open or closed position. All tanks and voids should be sounded just prior tostarting the experiment and also after the experiment. Specific gravity of the liquids in thetanks should be taken and recorded. The lengths of the pendulums or u-tubes should bemeasured and recorded, the position of the pendulum wire installation should be verified toensure that the wire hangs from a knife edge to ensure a free swing of the wire. At this pointthe ship should be breasted out and basically free floating (all lines slack).

Appendix C-3

2. After the ship is determined ready for the test, all personnel onboard are instructed toremain in their assigned inclining experiment locations. Three draft readings are taken,individually at each of the three draft mark locations, the port and starboard readings should betaken simultaneously. Water samples should also be taken at this time from various locationsand depths along the side of the ship to determine slip water density.

3. The next step of the experiment is to measure the inclination, First, all six battens aremarked simultaneously to a zero point before any block movement takes place. A minimum oftwo movements to starboard and two to port are required. The distance each block is moved ismeasured from its initial position and recorded. After each block movement, and after the shiphas stabilized from the block movement, the signal to read the measurement of the inclinationis given. If the ship maintains some level of residual motion, the reading should be taken at themidpoint of the motion. Readings from all stations are taken simultaneously and marked on thebattens. To maintain accuracy of the experiment, a novice should not be placed in a position toread and record the markings of the battens, since this task normally requires experience andpractice to become proficient. 4. After each block movement, measurements are recorded and the tangents of the angles ofinclination are plotted against the moments of the inclining weights. A straight line plot isdesired, whereas variations in the straight line plot may indicate that conditions (wind, incorrectblock weight, incorrect pendulum or utube measurement, etc.) may have adversely influencedthe experiment. A plot other than a straight line should be investigated, and after checking insome cases some of the points of the plot may be discarded. If the plot is satisfactory, allbattens are to be collected for verification of markings, plot sheets and other data needed tocomplete the inclining report. 5. The last step of the experiment is to take one final set of tank soundings. The incliningcoordinator at this point shall announce the inclining experiment is complete.